[media] cec: improve dqevent documentation

The documentation for the cec_event_state_change struct was incomplete.
This patch documents what happens in the corner cases.

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