V4L/DVB (4596): Fix saa7115 miscalculation that breaks NTSC

This repairs a problem introduced by a commit earlier applied.
Thanks-to: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/video/saa7115.c

@@ -851,7 +851,7 @@ static int saa711x_set_size(struct i2c_client *client, int width, int height)
 
 	/* On 60Hz, it is using a higher Vertical Output Size */
 	if (!is_50hz)
-		res+=(480-HRES_60HZ)>>1;
+		res+=(HRES_60HZ-480)>>1;
 
 		/* height */
 	saa711x_write(client, R_CE_B_VERT_OUTPUT_WINDOW_LENGTH,