Fix warnings generated by gcc for ia32 builds:

'cast from pointer to integer of different size'
when casting from a pointer directly to a
64 bit number.  Added an intermediate cast to
UINTN.


git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@5009 6f19259b-4bc3-4df7-8a09-765794883524

MdeModulePkg/Universal/CapsuleRuntimeDxe/CapsuleService.c

@@ -95,7 +95,7 @@ Returns:
     // ScatterGatherList is only referenced if the capsules are defined to persist across
     // system reset. 
     //
-    if (ScatterGatherList == (EFI_PHYSICAL_ADDRESS) NULL) {
+    if (ScatterGatherList == (EFI_PHYSICAL_ADDRESS) (UINTN) NULL) {
       return EFI_INVALID_PARAMETER;
     } else {
       //