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/Universal/SetupBrowserDxe/Expression.c

@@ -3675,7 +3675,7 @@ EXPRESS_RESULT
 EvaluateExpressionList (
   IN FORM_EXPRESSION_LIST *ExpList,
   IN BOOLEAN              Evaluate,
-  IN FORM_BROWSER_FORMSET *FormSet, OPTIONAL
+  IN FORM_BROWSER_FORMSET *FormSet  OPTIONAL,
   IN FORM_BROWSER_FORM    *Form OPTIONAL
   )
 {