[media] af9035: Add support for IT930x USB bridge

[media] af9035: Add support for IT930x USB bridge

Add support for IT930x USB bridge and IT9303 reference design.

It is a DVB-T/T2/C tuner with the following components:
- IT9303 USB bridge
- Si2168-B40 demodulator
- Si2147-A30 tuner

The IT9303 requires firmware that can be downloaded here:
http://trsqr.net/olli/linux/firmwares/it930x/

The Si2168-B40 requires firmware, but the one that is used by PCTV 292e can be used.
http://palosaari.fi/linux/v4l-dvb/firmware/Si2168/Si2168-B40/

The Si2147-A30 tuner does not require firmware loading.

Signed-off-by: Olli Salonen <olli.salonen@iki.fi>
Reviewed-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>