media: v4l2-ctrl: Document V4L2_CID_CAMERA_SENSOR_ROTATION

Add documentation for the V4L2_CID_CAMERA_SENSOR_ROTATION camera
control. The newly added read-only control reports the rotation
correction to be applied to images before displaying them to the user.

Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>