[media] mt2063: Rewrite tuning logic

Several vars at set_parms functions were set, but unused.
 Remove them and change the logic to return -EINVAL if the
analog set_param is used for digital mode.

At the analog side, cleans the logic that sets the several
analog standards.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>