[media] cx24117: use hybrid_tuner_request/release_state to share state between multiple instances

...and remove the frontend pointer param from cx24117_attach()

Signed-off-by: Luis Alves <ljalvs@gmail.com>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>