Add basic support for NXP TDA8295 analog demod and TDA18271 tuner silicon.

TDA8295 + TDA8275a not yet tested.
TDA8290 + TDA18271 not yet supported.

Digital mode of TDA18271 not yet tested & needs more work.
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>