media: cec: fix remote control passthrough

The 'Press and Hold' operation was not correctly implemented, in
particular the requirement that the repeat doesn't start until
the second identical keypress arrives. The REP_DELAY value also
had to be adjusted (see the comment in the code) to achieve the
desired behavior.

The 'enabled_protocols' field was also never set, fix that too. Since
CEC is a fixed protocol the driver has to set this field.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>