drm/omap: dss: Cleanup error paths in output init functions

Rename the jump labels according to the cleanup they perform, not the
location they're accessed from, and move functions from error checks to
cleanup paths, and move reference handling to simplify cleanup.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>