[media] v4l2-common: Delete an unnecessary check before the function call "spi_unregister_device"

The spi_unregister_device() function tests whether its argument is NULL
and then returns immediately. Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/v4l2-core/v4l2-common.c

@@ -291,7 +291,7 @@ struct v4l2_subdev *v4l2_spi_new_subdev(struct v4l2_device *v4l2_dev,
 error:
 	/* If we have a client but no subdev, then something went wrong and
 	   we must unregister the client. */
-	if (spi && sd == NULL)
+	if (!sd)
 		spi_unregister_device(spi);
 
 	return sd;