media: i2c: imx214: Add vblank and hblank controls

Add vblank control to allow changing the framerate /
higher exposure values.

The vblank and hblank controls are needed for libcamera support.

While at it, fix the minimal exposure time according to the datasheet.

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>