media: imx274: remove non-indexed pointers from mode_table

mode_table[] has 3 members that are accessed based on their index, which
makes worth using an array.

The other members are always accessed with a constant index. This added
indirection gives no improvement and only makes code more verbose.

Remove these pointers from the array and access them directly.

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>