[media] cx23855: add support for DVBSky T9580 DVB-C/T2/S2 tuner

[media] cx23855: add support for DVBSky T9580 DVB-C/T2/S2 tuner

DVBSky T9580 is a dual tuner card with one DVB-T2/C tuner and one DVB-S2 tuner. It contains the following components:

- PCIe bridge: Conexant CX23885
- Demod for terrestrial/cable: Silicon Labs Si2168-A30
- Tuner for terrestrial/cable: Silicon Labs Si2158-A20
- Demod for sat: Montage DS3103
- Tuner for sat: Montage TS2022

This patch depends on Max Nibble's patch for m88ds3103 (see patchwork 25312: https://patchwork.linuxtv.org/patch/25312/ ).

3 firmwares are needed:
- Si2168-A30 demod and Si2158-A20 tuner: same as TechnoTrend CT2-4400, https://www.mail-archive.com/linux-media@vger.kernel.org/msg76944.html
- Montage DS3103 demod: same as PCTV 461e, Antti has it on his LinuxTV project page: http://palosaari.fi/linux/v4l-dvb/firmware/M88DS3103/

IR receiver is not supported.

Values in cx23885_gpio_setup, cx23885_card_setup and dvbsky_t9580_set_voltage as well as the EEPROM read function are taken from the manufacturer provided semi-open source driver. The drivers in question are Linux GPL'd media tree drivers for cx23885 modified by Max Nibble (nibble.max@gmail.com) with proprietary tuner/demod drivers. Max is aware of this patch and has approved my use of the values in this patch.

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