media: renesas: vsp1: Drop vsp1_entity_get_pad_format() wrapper

The vsp1_entity_get_pad_format() function is just a wrapper around
v4l2_subdev_state_get_format() without any added value. Drop it and call
v4l2_subdev_state_get_format() directly.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi+renesas@ideasonboard.com>