Drop the load/unload driver ops, as they are deprecated because of their
inherent races, with devices being visible to userspace before they are
fully initialized.

Move this code into the driver bind/unbind routines bracketed by the
proper drm_dev_alloc/register and drm_dev_unregister/unref calls.
Signed-off-by: NLucas Stach <l.stach@pengutronix.de>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>