[media] pvrusb2: fix 7MHz & 8MHz DVB-T tuner support for HVR1900 rev D1F5

The D1F5 revision of the WinTV HVR-1900 uses a tda18271c2 tuner
instead of a tda18271c1 tuner as used in revision D1E9. To
account for this, we must hardcode the frontend configuration
to use the same IF frequency configuration for both revisions
of the device.

6MHz DVB-T is unaffected by this issue, as the recommended
IF Frequency configuration for 6MHz DVB-T is the same on both
c1 and c2 revisions of the tda18271 tuner.

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Cc: Mike Isely <isely@pobox.com>
Cc: stable@kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>