MdeModulePkg DxeCore: Missing change for OEM reserved memory type at R17460

MdeModulePkg DxeCore: Missing change for OEM reserved memory type at R17460

At the end of CoreFreePoolI(), the check to see if it is a specific
memory type should also cover OEM reserved memory type.
It was missed when adding OEM reserved memory type support at R17460.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Feng Tian <feng.tian@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>