[media] adv7511: fix error return code in adv7511_probe()

Fix to return error code -ENOMEM from the i2c client register error
handling case instead of 0, as done elsewhere in this function.

Signed-off-by: Wei Yongjun <weiyj.lk@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>