Fix memory extendedSize type

Modify "extendedSize" type to support 64-bit environment.
The size_t type uses 8 bytes in a 64-bit environment, the
properties "MemorySizeInKB" and "MemoryConfiguredSpeedInMhz"
will get wrong values from smbios file.

Tested:
```
root@qbmc:~# busctl introspect xyz.openbmc_project.Smbios.MDR_V2 \
> /xyz/openbmc_project/inventory/system/chassis/motherboard/dimm0 \
> xyz.openbmc_project.Inventory.Item.Dimm
.AllowedSpeedsMT                        property  aq        0                                        emits-change writable
.CASLatencies                           property  q         0                                        emits-change writable
.ECC                                    property  s         "xyz.openbmc_project.Inventory.Item.D... emits-change writable
.FormFactor                             property  s         "xyz.openbmc_project.Inventory.Item.D... emits-change writable
.MaxMemorySpeedInMhz                    property  q         4800                                     emits-change writable
.MemoryAttributes                       property  y         2                                        emits-change writable
.MemoryConfiguredSpeedInMhz             property  q         1100                                     emits-change writable
.MemoryDataWidth                        property  q         64                                       emits-change writable
.MemoryDeviceLocator                    property  s         "P0 CHANNEL A DIMM0"                     emits-change writable
.MemoryMedia                            property  s         "xyz.openbmc_project.Inventory.Item.D... emits-change writable
.MemorySizeInKB                         property  t         3479875137107394560                      emits-change writable
.MemoryTotalWidth                       property  q         0                                        emits-change writable
...
```
After
```
root@qbmc:~# busctl introspect xyz.openbmc_project.Smbios.MDR_V2 \
> /xyz/openbmc_project/inventory/system/chassis/motherboard/dimm0 \
> xyz.openbmc_project.Inventory.Item.Dimm
NAME                                    TYPE      SIGNATURE RESULT/VALUE                             FLAGS
.AllowedSpeedsMT                        property  aq        0                                        emits-change writable
.CASLatencies                           property  q         0                                        emits-change writable
.ECC                                    property  s         "xyz.openbmc_project.Inventory.Item.D... emits-change writable
.FormFactor                             property  s         "xyz.openbmc_project.Inventory.Item.D... emits-change writable
.MaxMemorySpeedInMhz                    property  q         4800                                     emits-change writable
.MemoryAttributes                       property  y         2                                        emits-change writable
.MemoryConfiguredSpeedInMhz             property  q         4800                                     emits-change writable
.MemoryDataWidth                        property  q         64                                       emits-change writable
.MemoryDeviceLocator                    property  s         "P0 CHANNEL A DIMM0"                     emits-change writable
.MemoryMedia                            property  s         "xyz.openbmc_project.Inventory.Item.D... emits-change writable
.MemorySizeInKB                         property  t         33554432                                 emits-change writable
.MemoryTotalWidth                       property  q         0                                        emits-change writable
...
```

Change-Id: I205de7df72269e472143ea3a3fc2f6f9e4af56ee
Signed-off-by: Joseph Fu <joseph.fu@quantatw.com>
diff --git a/src/dimm.cpp b/src/dimm.cpp
index 8690969..6102627 100644
--- a/src/dimm.cpp
+++ b/src/dimm.cpp
@@ -156,7 +156,7 @@
 static constexpr uint16_t dimmSizeUnit = 1024;
 void Dimm::dimmSize(const uint16_t size)
 {
-    size_t result = size & maxOldDimmSize;
+    uint32_t result = size & maxOldDimmSize;
     if (0 == (size & baseNewVersionDimmSize))
     {
         result = result * dimmSizeUnit;
@@ -164,7 +164,7 @@
     memorySizeInKB(result);
 }
 
-void Dimm::dimmSizeExt(size_t size)
+void Dimm::dimmSizeExt(uint32_t size)
 {
     size = size * dimmSizeUnit;
     memorySizeInKB(size);