media: i2c: imx214: Drop IMX214_REG_EXPOSURE from mode reg arrays

The IMX214_REG_EXPOSURE is configured twice, once with a hardcoded value
in the mode_<res> registers arrays, and once via v4l2_ctrl_ops. The
latter is enough, drop the former.

Acked-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: André Apitzsch <git@apitzsch.eu>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>