mailbox: fix merge

Author: scpcom

drivers/mailbox/mailbox.c

@@ -117,7 +117,6 @@ static void poll_txdone(struct timer_list *t)
 	struct mbox_controller *mbox = from_timer(mbox, t, poll);
 	bool txdone, resched = false;
 	int i;
-	unsigned long flags;
 
 	for (i = 0; i < mbox->num_chans; i++) {
 		struct mbox_chan *chan = &mbox->chans[i];