[media] add a driver for mb86a20s

This adds the trivial bits to mb86a20s. As the driver won't touch
at the channel/layer parameters, this may not be enough for
receiving all channels, especially ISDB-Tsb, but the driver worked
properly for receiving video channels on my tests.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>