[media] ir-rx51: port to rc-core

This driver was written using lirc since rc-core did not support
transmitter-only hardware at that time. Now that it does, port
this driver.

Compile tested only.

Signed-off-by: Sean Young <sean@mess.org>
Cc: Timo Kokkonen <timo.t.kokkonen@iki.fi>
Cc: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>