[media] doc-rst: Clean up raw bayer pixel format definitions

- Explicitly state that the most significant n bits are zeroed on 10 and
  12 bpp formats.
- Remove extra comma from the last entry of the format list
- Add a missing colon before a list
- Use figures versus word numerals consistently

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>