drm/i2c: tda998x: don't register the connector

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

As drm_dev_register() now registers all of the connectors anyway,
there's no need to explicitly do it in individual drivers so remove
the calls to drm_connector_register()/drm_connector_unregister().

This allows componentised drivers to use tda998x without having racy
initialisation.

Signed-off-by: Brian Starkey <brian.starkey@arm.com>
Reviewed-by: Liviu Dudau <Liviu.Dudau@arm.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1469444148-19003-1-git-send-email-brian.starkey@arm.com
Link: http://patchwork.freedesktop.org/patch/msgid/545C835D.1050008@arm.com