MdePkg: 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>

MdePkg/Include/Protocol/HiiConfigKeyword.h

@@ -175,8 +175,8 @@ typedef
 EFI_STATUS
 (EFIAPI *EFI_CONFIG_KEYWORD_HANDLER_GET_DATA) (
   IN EFI_CONFIG_KEYWORD_HANDLER_PROTOCOL  *This,
-  IN CONST EFI_STRING                     NameSpaceId, OPTIONAL
-  IN CONST EFI_STRING                     KeywordString, OPTIONAL
+  IN CONST EFI_STRING                     NameSpaceId  OPTIONAL,
+  IN CONST EFI_STRING                     KeywordString  OPTIONAL,
   OUT EFI_STRING                          *Progress,
   OUT UINT32                              *ProgressErr,
   OUT EFI_STRING                          *Results
@@ -196,4 +196,3 @@ struct _EFI_CONFIG_KEYWORD_HANDLER_PROTOCOL {
 extern EFI_GUID gEfiConfigKeywordHandlerProtocolGuid;
 
 #endif
-