drm/tilcdc: fix release order on exit

Unregister resources in the correct order on tilcdc_drm_fini, which is
the reverse order they were registered during tilcdc_drm_init.

This also means unregistering the driver before releasing its resources.

Signed-off-by: Guido Martínez <guido@vanguardiasur.com.ar>
Tested-by: Darren Etheridge <detheridge@ti.com>
Cc: <stable@vger.kernel.org> #v3.9+
Signed-off-by: Dave Airlie <airlied@redhat.com>