media: ov5647: Add support for get_selection()

Support the get_selection() pad operation to report the device
full pixel array size, the currently applied analogue crop rectangle and
the active pixel array dimensions.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>