SignedCapsulePkg: 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: Jian J Wang <jian.j.wang@intel.com>

SignedCapsulePkg/Library/EdkiiSystemCapsuleLib/EdkiiSystemCapsuleLib.c

@@ -661,7 +661,7 @@ CapsuleAuthenticateSystemFirmware (
 VOID
 EFIAPI
 EdkiiSystemCapsuleLibPcdCallBack (
-  IN        CONST GUID        *CallBackGuid, OPTIONAL
+  IN        CONST GUID        *CallBackGuid  OPTIONAL,
   IN        UINTN             CallBackToken,
   IN  OUT   VOID              *TokenData,
   IN        UINTN             TokenDataSize

SignedCapsulePkg/Library/PlatformFlashAccessLibNull/PlatformFlashAccessLibNull.c

@@ -51,7 +51,7 @@ PerformFlashWriteWithProgress (
   IN FLASH_ADDRESS_TYPE                             FlashAddressType,
   IN VOID                                           *Buffer,
   IN UINTN                                          Length,
-  IN EFI_FIRMWARE_MANAGEMENT_UPDATE_IMAGE_PROGRESS  Progress,        OPTIONAL
+  IN EFI_FIRMWARE_MANAGEMENT_UPDATE_IMAGE_PROGRESS  Progress         OPTIONAL,
   IN UINTN                                          StartPercentage,
   IN UINTN                                          EndPercentage
   )
@@ -98,4 +98,3 @@ PerformFlashWrite (
            0
            );
 }
-