MdeModulePkg: 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: Liming Gao <gaoliming@byosoft.com.cn>

MdeModulePkg/Library/DxeCapsuleLibFmp/DxeCapsuleProcessLib.c

@@ -148,7 +148,7 @@ EFI_STATUS
 EFIAPI
 ProcessThisCapsuleImage (
   IN EFI_CAPSULE_HEADER  *CapsuleHeader,
-  IN CHAR16              *CapFileName,  OPTIONAL
+  IN CHAR16              *CapFileName   OPTIONAL,
   OUT BOOLEAN            *ResetRequired OPTIONAL
   );