media: imx: add capture compose rectangle

Allowing to compose captured images into larger memory buffers
will let us lift alignment restrictions on CSI crop width.

For now all compose rectangles are identical to the complete
frame width / height. This will be changed in the next patches.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Steve Longerbeam <slongerbeam@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>