[media] cec: select CEC_CORE instead of depend on it

The CEC framework is used by both drm and media. That makes it tricky
to get the dependencies right.

This patch moves the CEC_CORE and MEDIA_CEC_NOTIFIER config options
out of the media menu and instead drivers that want to use CEC should
select CEC_CORE and MEDIA_CEC_NOTIFIER (if needed).

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>