Connectors shouldn't be registered until the rest of the whole device
is set up, so that consistent state is presented to userspace.

As such, remove the calls to drm_connector_register() and
drm_connector_unregister() from tda998x, as these are now handled by
drm_dev_(un)register() itself.

To work with this change, the mali-dp and hdlcd bind and unbind
sequences have to be reordered, to ensure that the componentised
encoder/connector is bound before drm_dev_register() registers all
connectors. Similarly, the device must be unregistered before the
component is unbound.

Altogether, this allows other drivers using tda998x to be
de-midlayered, and to have less racy initialisation of their components.

Splitting this commit into three (one per driver) isn't possible without
intermediate breakage, so it is all squashed together here.
Suggested-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Brian Starkey <brian.starkey@arm.com>
Reviewed-by: Liviu Dudau <Liviu.Dudau@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>