V4L/DVB (7448): Add support for Kworld ATSC 120

This board has a s5h1409 demod, plus a xc30x8 tuner (probably, xc3018).

This patch adds proper support for radio, video, s-video, composite and ATSC.
However, support for radio and video depends on having s5h1409 i2c gate open,
otherwise, xc30x8 chip won't be visible.

For a better support, some rework is needed on cx88 driver, to allow adding
xc30x8 to i2c bus without sending i2c 0 byte reading to 0xc2 address.

Thanks to Vanessa Ezekowitz <vanessaezekowitz@gmail.com> for helping to figure
out the proper parameters for s5h1409 and the GPIO pins used by each
configuration.

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>