Instead of checking everywhere there for 3 symbols, use instead
IS_ENABLED macro.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Raise the DVB frontends one level up, as the intention is to remove
the drivers/media/dvb directory.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

On our tests with Leadership ISDBT, the s921 frontend were not work. As its
design contained some weird things, it ended to be easier to just re-write
it, getting another frontend as an example (cx24123).

As the old s921 driver weren't used, there's no regression. Some info from
the old frontend were used as a way to double check the behavior that were
noticed on the USB dumps retrieved from Leadership driver.
Signed-off-by: NDouglas Schilling Landgraf <dougsland@redhat.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>