UefiCpuPkg: Change OPTIONAL keyword usage style

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3760

Update all use of ', OPTIONAL' to ' OPTIONAL,' for function params.

Cc: Andrew Fish <afish@apple.com>
Cc: Leif Lindholm <leif@nuviainc.com>
Cc: Michael Kubacki <michael.kubacki@microsoft.com>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>

UefiCpuPkg/Library/MtrrLib/UnitTest/MtrrLibUnitTest.h

@@ -129,7 +129,7 @@ VOID
 GenerateRandomMtrrPair (
   IN  UINT32                 PhysicalAddressBits,
   IN  MTRR_MEMORY_CACHE_TYPE CacheType,
-  OUT MTRR_VARIABLE_SETTING  *MtrrPair,       OPTIONAL
+  OUT MTRR_VARIABLE_SETTING  *MtrrPair        OPTIONAL,
   OUT MTRR_MEMORY_RANGE      *MtrrMemoryRange OPTIONAL
   );