Despite its name, tuner-simple has a complex logic to set freqs ;)

Basically, it can be called by two different ways: via set_params()
or via calc_regs() callbacks. Both are bound to the DVBv3 API.
Also, set_params internally calls calc_regs().

In order to get rid of DVBv3 params at set_params(), it shouldn't
call calc_regs() anymore. The code duplication is very small,
as most of the code there is just to check for invalid parameters.

With regards to calc_regs(), it should still trust on bandwidth and
frequency parameters passed via DVBv3, until a later patch fixes
it.
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>