[media] media: lirc_dev: remove support for manually specifying minor number

All users of lirc_register_driver() uses dynamic minor allocation,
therefore we can remove the ability to explicitly request a given number.

This changes the function prototype of lirc_unregister_driver() to also
take a struct lirc_driver pointer as the sole argument.

Signed-off-by: David Härdeman <david@hardeman.nu>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>