[media] af9035: minor changes for af9035_fc0011_tuner_callback()

Change function to use same logic than existing functions.
Debugs log writings are done in error case, earlier it was
just returning error code.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>