V4L/DVB (9774): tda827x: fix returned frequency

Probably due to a removed code, tda827x were doing some wrong calculus at the
returned frequency. I suspect that the original idea were to return the
programmed divisor converted into frequency again.

However, the current code is sometimes multiplying the programmed frequency by
62500, and, on other cases, like radio, it dividing it by 1000.

Instead of doing such math, let's just store the frequency value as requested by
the caller module.

Cc: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>