firedtv: dvb_frontend_info for FireDTV S2, fix "frequency limits undefined" error

I found that the function fdtv_frontend_init in the file firedtv-fe.c was
missing a case for FIREDTV_DVB_S2 which resulted in "frequency limits
undefined" errors in syslog.

Signed-off-by: Beat Michel Liechti <bml303@gmail.com>

Change by Stefan R: combine it with case case FIREDTV_DVB_S as
originally suggested by Beat Michel.  This enables FE_CAN_FEC_AUTO also
for FireDTV-S2 devices which is possible as long as only DVB-S channels
are used.  FE_CAN_FEC_AUTO would be wrong for DVB-S2 channels, but those
cannot be used yet since the driver is not yet converted to S2API.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>