[media] adv7511: fix quantization range handling

Commit 1fb69bfd (adv7511: improve
colorspace handling) introduced a number of bugs, specifically with
regards to YCbCr output and quantization range handling:

- if the output is not RGB, then disable the full-to-limited range
  CSC matrix since that is meant for RGB formats. YCbCr formats are
  always limited range, so there is nothing to convert. (OK, full
  range YCbCr is possible, but we don't support that right now).

- the mediabus code that was passed to adv7511_set_fmt was always cleared
  by the memset in adv7511_fill_format. This made it effectively impossible
  to select YCbCr output.

- adv7511_set_fmt never updated the rgb quantization range.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>