Fix DVB-S/S2 support

The LNBf settings were not being passed to libdvbv5, causing tune
to fail. Rework the code to use the LNBf types supported by the
library, and to set it accordingly.

BUG: 364401

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