media: atomisp: Add target validation to atomisp_subdev_set_selection()

As the 2 comments in the function already say both the sink and the source
pads only support setting the selection for 1 target:

		/* Only crop target supported on sink pad. */
		/* Only compose target is supported on source pads. */

Validate that the passed in target actually matches these expectations.

Link: https://lore.kernel.org/r/20230529103741.11904-11-hdegoede@redhat.com



Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>