OvmfPkg: 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: Andrew Fish <afish@apple.com>

OvmfPkg/Library/QemuFwCfgS3Lib/QemuFwCfgS3Base.c

@@ -96,7 +96,7 @@ RETURN_STATUS
 EFIAPI
 QemuFwCfgS3CallWhenBootScriptReady (
   IN     FW_CFG_BOOT_SCRIPT_CALLBACK_FUNCTION *Callback,
-  IN OUT VOID                                 *Context,          OPTIONAL
+  IN OUT VOID                                 *Context           OPTIONAL,
   IN     UINTN                                ScratchBufferSize
   )
 {