media: imx274: rename and reorder register address definitions

Most registers are defined using the name used in the datasheet.
E.g. the defines for the HMAX register are IMX274_HMAX_REG_*.

Rename the SHR and VMAX register accordingly. Also move them close to
related registers: SHR close to SVR, VMAX close to HMAX.

Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>