atomisp/imx: Fix locking bug on error path

This was reported by Dan Carpenter. When we error with an IMX 227 we don't release
the lock and the sensor would then hang.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/media/atomisp/i2c/imx/imx.c

@@ -454,8 +454,10 @@ static int imx_set_exposure_gain(struct v4l2_subdev *sd, u16 coarse_itg,
 
 	if (dev->sensor_id == IMX227_ID) {
 		ret = imx_write_reg_array(client, imx_param_hold);
-		if (ret)
+		if (ret) {
+			mutex_unlock(&dev->input_lock);
 			return ret;
+		}
 	}
 
 	/* For imx175, setting gain must be delayed by one */