V4L/DVB (3964): Bt8xx/bttv-cards.c: fix off-by-one errors

This patch fixes two off-by-one errors spotted by the Coverity checker.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/video/bt8xx/bttv-cards.c

@@ -2991,13 +2991,13 @@ void __devinit bttv_idcard(struct bttv *btv)
 
 	if (UNSET != audiomux[0]) {
 		gpiobits = 0;
-		for (i = 0; i < 5; i++) {
+		for (i = 0; i < 4; i++) {
 			bttv_tvcards[btv->c.type].gpiomux[i] = audiomux[i];
 			gpiobits |= audiomux[i];
 		}
 	} else {
 		gpiobits = audioall;
-		for (i = 0; i < 5; i++) {
+		for (i = 0; i < 4; i++) {
 			bttv_tvcards[btv->c.type].gpiomux[i] = audioall;
 		}
 	}