V4L/DVB (9372): Minor fixes to the saa7110 driver

V4L/DVB (9372): Minor fixes to the saa7110 driver

* Apparently the author of the saa7110 driver was confused by the
  number of outputs returned by DECODER_GET_CAPABILITIES. Of course a
  decoder chip has no analog ouputs, but it must have at least one
  digital output.

* Fix an off-by-one error when checking the input value of
  DECODER_SET_INPUT.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>