drm/tilcdc: call drm_put_dev directly from ->remove

tilcdc already stores the drm_device in the driver data pointer. So
use that.

Cc: Rob Clark <robdclark@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>