media: i2c: imx290: Define more register macros

Define macros for all registers programmed by the driver for which
documentation is available to increase readability. This starts making
use of 16-bit registers in the register arrays, so the value field has
to be increased to 32 bits.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>