[media] firedtv: support for PSK8 for S2 devices. To watch HD

Add support for tuning with PSK8 modulation, pilot and rolloff
with the S2 versions of firedtv.

Signed-off-by: Tommy Jonsson <quazzie2@gmail.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (trivial simplification)
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>