media: dvb-usb/friio, dvb-usb-v2/gl861: decompose friio and merge with gl861

Friio device contains "gl861" bridge and "tc90522" demod,
for which the separate drivers are already in the kernel.
But friio driver was monolithic and did not use them,
practically copying those features.
This patch decomposes friio driver into sub drivers and
re-uses existing ones, thus reduces some code.

It adds some features to gl861,
to support the friio-specific init/config of the devices
and implement i2c communications to the tuner via demod
with USB vendor requests.

[mchehab+samsung@kernel.org: fix merge conflicts]
Signed-off-by: Akihiro Tsukada <tskd08@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>