[media] cec: add compat32 ioctl support

The CEC ioctls didn't have compat32 support, so they returned -ENOTTY
when used in a 32 bit application on a 64 bit kernel.

Since all the CEC ioctls are 32-bit compatible adding support for this
API is trivial.

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