[media] DVB: Query DVB frontend delivery capabilities

[media] DVB: Query DVB frontend delivery capabilities

 Currently, for any multi-standard frontend it is assumed that it just
 has a single standard capability. This is fine in some cases, but
 makes things hard when there are incompatible standards in conjuction.
 Eg: DVB-S can be seen as a subset of DVB-S2, but the same doesn't hold
 the same for DSS. This is not specific to any driver as it is, but a
 generic issue. This was handled correctly in the multiproto tree,
 while such functionality is missing from the v5 API update.

 http://www.linuxtv.org/pipermail/vdr/2008-November/018417.html

 Later on a FE_CAN_2G_MODULATION was added as a hack to workaround this
 issue in the v5 API, but that hack is incapable of addressing the
 issue, as it can be used to simply distinguish between DVB-S and
 DVB-S2 alone, or another X vs X2 modulation. If there are more systems,
 then you have a potential issue.

 An application needs to query the device capabilities before requesting
 any operation from the device.

Signed-off-by: Manu Abraham <abraham.manu@gmail.com>
Acked-by: Andreas Oberritter <obi@linuxtv.org>
Acked-by: Oliver Endriss <o.endriss@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>