To make vsp1_subdev_set_pad_format() usable by entities that support
selection rectangles, we need to reset the crop and compose rectangles
when setting the format on the sink pad. Do so and replace the custom
set_fmt implementation of the histogram code by a call to
vsp1_subdev_set_pad_format().

Resetting the crop and compose rectangles for entities that don't
support crop and compose has no adverse effect as the rectangles are
ignored anyway.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>