media: i2c: ov4689: Clean up and annotate the register table

media: i2c: ov4689: Clean up and annotate the register table

Many values in the register table are actually power-on
defaults. Remove those and also unused HDR exposures and gains.
Annotate the remaining values using the publicly available datasheet
to facilitate further development. No functional change intended.

Signed-off-by: Mikhail Rudenko <mike.rudenko@gmail.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>