There are several fields on rc_dev that drivers can benefit. Allow drivers
to pass it as a parameter to the driver.

For now, the rc_dev parameter is optional. If drivers don't pass it, create
them internally. However, the best is to create rc_dev inside the drivers,
in order to fill other fields, like open(), close(), driver_name, etc.
So, a latter patch making it mandatory and changing the caller drivers is
welcome.
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>