media: uapi: Add controls for the THP7312 ISP

The THP7312 is an external ISP from THine. As such, it implements a
large number of parameters to control all aspects of the image
processing. Many of those controls are already standard in V4L2, but
some are fairly device-specific.

Reserve a range of 32 controls for the device. The driver will implement
4 device-specific controls to start with, define and document them. 28
additional device-specific controls should be enough for future
development.

Co-developed-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>