[media] zc3xx: don't go past quality array

drivers/media/usb/gspca/zc3xx.c:6363 zcxx_s_ctrl() error: buffer overflow 'jpeg_qual' 3 <= 3

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
diff --git a/drivers/media/usb/gspca/zc3xx.c b/drivers/media/usb/gspca/zc3xx.c
index d3e1b6d..3762a04 100644
--- a/drivers/media/usb/gspca/zc3xx.c
+++ b/drivers/media/usb/gspca/zc3xx.c
@@ -6360,7 +6360,7 @@
 			if (ctrl->val <= jpeg_qual[i])
 				break;
 		}
-		if (i > 0 && i == qual && ctrl->val < jpeg_qual[i])
+		if (i == ARRAY_SIZE(jpeg_qual) || (i > 0 && i == qual && ctrl->val < jpeg_qual[i]))
 			i--;
 
 		/* With high quality settings we need max bandwidth */