[media] mt2063: Fix analog/digital set params logic

The driver were using a hacky way of setting analog and digital
frequencies. Remove the hack and properly add the tuner logic for
each supported type of standard.

I was tempted to add more standards there, like SECAM and to fix
radio (as stepping seems broken), but I opted to keep it as-is,
as tests would be needed to add additional standards.

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