drm/omap: fix use of freed memory

omap_connector_destroy() does:

kfree(omap_connector);
omapdss_device_put(omap_connector->output);
omapdss_device_put(omap_connector->display);

Fix this by moving the kfree after the omapdss_device_puts.

This bug was introduced in 949ea2ef

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>