media: dvb: convert tuner_info frequencies to Hz

Right now, satellite tuner drivers specify frequencies in kHz,
while terrestrial/cable ones specify in Hz. That's confusing
for developers.

However, the main problem is that universal tuners capable
of handling both satellite and non-satelite delivery systems
are appearing. We end by needing to hack the drivers in
order to support such hybrid tuners.

So, convert everything to specify tuner frequencies in Hz.

Plese notice that a similar patch is also needed for frontends.

Tested-by: Katsuhiro Suzuki <suzuki.katsuhiro@socionext.com>
Acked-by: Michael Büsch <m@bues.ch>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>