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

Fix to return -ENOMEM in the new i2c client and create workqueue error
handling case instead of 0, as done elsewhere in this function.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>