media: omap3isp: Ignore endpoints with invalid configuration

If endpoint has an invalid configuration, ignore it instead of happily
proceeding to use it nonetheless. Ignoring such an endpoint is better than
failing since there could be multiple endpoints, only some of which are
bad.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Tested-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>