NetworkPkg: 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: Maciej Rabeda <maciej.rabeda@linux.intel.com>

NetworkPkg/SnpDxe/Get_status.c

@@ -195,7 +195,7 @@ EFI_STATUS
 EFIAPI
 SnpUndi32GetStatus (
   IN EFI_SIMPLE_NETWORK_PROTOCOL *This,
-  OUT UINT32                     *InterruptStatus, OPTIONAL
+  OUT UINT32                     *InterruptStatus  OPTIONAL,
   OUT VOID                       **TxBuf           OPTIONAL
   )
 {