staging: slicoss: Fix possible reuse of freed memory in timer function

Do not call kfree() till timer function is finished.

[This was found using grep. Compiled tested only]
Signed-off-by: Kirill Tkhai <tkhai@yandex.ru>
CC: Joe Perches <joe@perches.com>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/slicoss/slicoss.c

@@ -2970,7 +2970,7 @@ static void slic_card_cleanup(struct sliccard *card)
 {
 	if (card->loadtimerset) {
 		card->loadtimerset = 0;
-		del_timer(&card->loadtimer);
+		del_timer_sync(&card->loadtimer);
 	}
 
 	slic_debug_card_destroy(card);