[media] DVB: dvb_frontend: Fix compatibility criteria for satellite receivers

  identify a satellite receiver by its 'delivery_system' instead of
  'modulation', which may overlap between different delivery systems.

Signed-off-by: Andreas Oberritter <obi@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>