media: i2c: Introduce a driver for the Techwell TW9900 decoder

The Techwell video decoder supports PAL, NTSC standards and
has a parallel BT.656 output interface.

This commit adds support for this device, with basic support
for NTSC and PAL, along with brightness and contrast controls.

The TW9900 is capable of automatic standard detection. This
driver is implemented with support for PAL and NTSC
autodetection.

Reviewed-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Mehdi Djait <mehdi.djait@bootlin.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>