Dimm memory size support

This commit will calculate the memory size for Dimm and
populate the value with property MemorySizeinKB on dbus.

Test- Tested on simics 2s2u

Set the property with dummy value-

root@rain71bmc:/tmp#  busctl introspect  xyz.openbmc_project.Inventory.Manager  /xyz/openbmc_project/inventory/system/chassis/motherboard/dimm0| grep -e MemorySizeInKB -e  Present -e PrettyName -e Model  -e PartNumber  -e SerialNumber
.Model                                                property  s         "327A"                                   emits-change writable
.PartNumber                                           property  s         "78P6574"                                emits-change writable
.SerialNumber                                         property  s         "YH301T01P00G"                           emits-change writable
.SparePartNumber                                      property  s         ""                                       emits-change writable
.SubModel                                             property  s         ""                                       emits-change writable
.Present                                              property  b         true                                     emits-change writable
.PrettyName                                           property  s         "Memory DIMM"                            emits-change writable
.MemorySizeInKB                                       property  u         33554432                                 emits-change writable
root@rain71bmc:/tmp#

Signed-off-by: Alpana Kumari <alpankum@in.ibm.com>
Change-Id: I70e5bc3f538379f9891ae0ede6cdf09a585520a4
diff --git a/const.hpp b/const.hpp
index e173e89..5cab687 100644
--- a/const.hpp
+++ b/const.hpp
@@ -68,6 +68,7 @@
 static constexpr auto PART_NUM_LEN = 7;
 static constexpr auto SERIAL_NUM_LEN = 12;
 static constexpr auto CCIN_LEN = 4;
+static constexpr auto CONVERT_MB_TO_KB = 1024;
 
 using namespace std::string_literals;
 constexpr auto pimPath = "/xyz/openbmc_project/inventory";