[media] saa7115: fix querystd

Return V4L2_STD_UNKNOWN if no signal is detected.

Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/i2c/saa7115.c

···
 			*std &= V4L2_STD_SECAM;
 			break;
 		default:
+			*std = V4L2_STD_UNKNOWN;
 			/* Can't detect anything */
 			break;
 		}
···
 	v4l2_dbg(1, debug, sd, "Status byte 2 (0x1f)=0x%02x\n", reg1f);
 
 	/* horizontal/vertical not locked */
-	if (reg1f & 0x40)
+	if (reg1f & 0x40) {
+		*std = V4L2_STD_UNKNOWN;
 		goto ret;
+	}
 
 	if (reg1f & 0x20)
 		*std &= V4L2_STD_525_60;