V4L/DVB (11065): au8522: add support for analog side of demodulator

Add support for the analog functionality in the au8522 analog/digital
demodulator

Thanks to Michael Krufky <mkrufky@linuxtv.org> and Steven Toth
<stoth@linuxtv.org> for providing sample hardware, engineering level support,
and testing.

Signed-off-by: Devin Heitmueller <dheitmueller@linuxtv.org>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
[mchehab: renamed drivers/media/video/au8522_decoder.c as drivers/media/dvb/frontends/au8522_decoder.c to avoid breaking bisect]
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>