LPC-Snoop event isn't registered into event loop

The `reporterSource` is constructs in the if-statement but destructed right
after leaving the scope, so the event never be registered into event loop.

Tested with verbose mode, without a snoop device is okay.
```
root@ast2600-emmc:/# /tmp/snoopd -b 1 -v

^C
```

With a snoop device is working correctly.
```
root@ast2600-emmc:/# /tmp/snoopd -b 1 -v -d /dev/aspeed-lpc-snoop0
Code: 0x1
Code: 0x3
Code: 0x4
Code: 0x2
Code: 0x3
Code: 0x4
Code: 0x5
Code: 0xc
Code: 0xd
Code: 0x15
Code: 0x19
Code: 0x0
Code: 0x2
Code: 0x7f
Code: 0x0
Code: 0xf
Code: 0x3
Code: 0x48
Code: 0x49
Code: 0x4a
Code: 0x4d
Code: 0x50
Code: 0x15
```

Signed-off-by: Troy Lee <troy_lee@aspeedtech.com>
Change-Id: I5b9c186eccaf1277f07c9d866dd875cde1ab385d
diff --git a/main.cpp b/main.cpp
index d25fd6f..74d8072 100644
--- a/main.cpp
+++ b/main.cpp
@@ -173,10 +173,10 @@
     try
     {
         sdeventplus::Event event = sdeventplus::Event::get_default();
+        std::unique_ptr<sdeventplus::source::IO> reporterSource;
         if (postFd > 0)
         {
-
-            sdeventplus::source::IO reporterSource(
+            reporterSource = std::make_unique<sdeventplus::source::IO>(
                 event, postFd, EPOLLIN | EPOLLET,
                 std::bind(PostCodeEventHandler, std::placeholders::_1,
                           std::placeholders::_2, std::placeholders::_3,