drm/connector: Reorder headers

Unlike most of the other files in DRM, and Linux in general, the headers in
drm_connector.c aren't sorted alphabetically. Let's fix that.

Acked-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>