V4L/DVB (8949): xc5000: allow multiple driver instances for the same hardware to share state

Convert xc5000 to use the hybrid_tuner_request_state and
hybrid_tuner_release_state macros to manage state sharing between
hybrid tuner instances.

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>