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/Include/Library/LockBoxLib.h

@@ -117,7 +117,7 @@ RETURN_STATUS
 EFIAPI
 RestoreLockBox (
   IN  GUID                        *Guid,
-  IN  VOID                        *Buffer, OPTIONAL
+  IN  VOID                        *Buffer  OPTIONAL,
   IN  OUT UINTN                   *Length  OPTIONAL
   );