drm/omap: rearrange includes in omapdss.h

Drop "uapi/" and rearrange alphabetically.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201103080310.164453-5-tomi.valkeinen@ti.com