staging/vt6656: Fix sparse warning constant 0xffffffff00000000U is so big it is unsigned long

Since 7c65fa2a
'staging: vt6656: Remove QWORD from source and replace with u64.'
a new sparse warning showed up:

'drivers/staging/vt6656/card.c:798:26: sparse: constant
 0xffffffff00000000U is so big it is unsigned long'

-> Append L to fix the warning.
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Cc: Forest Bond <forest@alittletooquiet.net>
Cc: Malcolm Priestley <tvboxspy@gmail.com>
Cc: "Justin P. Mattock" <justinmattock@gmail.com>
Cc: Marcos Paulo de Souza <marcos.souza.org@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vt6656/card.c

@@ -790,7 +790,7 @@ u64 CARDqGetNextTBTT(u64 qwTSF, WORD wBeaconInterval)
 	if ((~uLowNextTBTT) < uLowRemain)
 		qwTSF = ((qwTSF >> 32) + 1) << 32;
 
-	qwTSF = (qwTSF & 0xffffffff00000000U) |
+	qwTSF = (qwTSF & 0xffffffff00000000UL) |
 		(u64)(uLowNextTBTT + uLowRemain);
 
     return (qwTSF);