V4L/DVB (6881): include struct analog_demod_ops directly inside struct dvb_frontend

Rather than using a pointer, include struct analog_demod_ops directly
inside struct dvb_frontend.  This will allow us to use dvb_attach in
the future, along with removing the need to check the ops structure
before having to check the pointer to the method being called.

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