drm/udl: Pass rectangle directly to udl_handle_damage()

Just for some code simplification.

Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/87tu5iauw4.wl-tiwai@suse.de