Check that we do have a valid port in an endpoint, return an error if not.
Signed-off-by: NSakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: NSebastian Reichel <sebastian.reichel@collabora.co.uk>
Tested-by: NPavel Machek <pavel@ucw.cz>
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>