V4L/DVB (12116): cx23885: ensure correct IF freq is used on HVR1200 & HVR1700

Ensure that we're programming the tda18271 tuner with the correct
IF frequencies to match the programming of the TDA10048 DVB-T demod
for the HVR1200 and HVR1700 products.

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