media: cx231xx: Fix the S-Video capture on August VGB100

media: cx231xx: Fix the S-Video capture on August VGB100

There are three separate issues preventing color capture with S-Video
on August VGB100 with the cx231xx driver (same vid/pid as OTG102):

1. `cx231xx_set_decoder_video_input` is called with a u32 passed
   as its third argument, yet this functions expects a u8 instead.
   Some information about the configuration of the video mux is lost
   in the conversion, so that ch2 and ch3 do not get set by
   `cx231xx_afe_set_input_mux` (expecting a u32 but being passed a u8).

2. The input pin for the chroma signal is not correctly specified
   in cx231xx-cards.c, which can be verified by looking at the inf file
   coming with the VGB100 and OTG102' drivers for Windows.
   The mistake in the cx231xx driver likely stems from a wrong comment
   in the same file, suggesting VIN1_2 for chroma,
   while VIN3_2 is actually used.

3. Even after fixing the two issues above, the captured stream remains
   essentially B&W (although acquiring some pale green shades, suggesting
   we're moving in the right direction).
   After tests with somewhat random changes, it was found that removing
   `CX25840_SVIDEO_ON` from the vmux configuration in cx231xx-cards.c
   results in a captured stream with the expected colors.

Signed-off-by: Fabio Luongo <f.langufo.l@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>