ClearQAM is currently not working. Add support for it too.
Unlikely other ATSC tuners, though, this device will not
auto-detect between ATSC and ClearQAM. So, the delivery
system should be properly set.

Also, this frontend seems to also support DVB-C annex A/C. Add
experimental support for them.
Acked-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>