drm: exynos: exynos_hdmi: use cec_notifier_conn_(un)register

Use the new cec_notifier_conn_(un)register() functions to
(un)register the notifier for the HDMI connector, and fill in
the cec_connector_info.

Changes since v7:
	- err_runtime_disable -> err_rpm_disable
Changes since v2:
	- removed unnecessary call to invalidate phys address before
	deregistering the notifier,
	- use cec_notifier_phys_addr_invalidate instead of setting
	invalid address on a notifier.

Signed-off-by: Dariusz Marcinkiewicz <darekm@google.com>
Tested-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
[hverkuil-cisco@xs4all.nl: use 'if (!hdata->notifier)' instead of '== NULL']
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Link: https://patchwork.freedesktop.org/patch/msgid/20190828123415.139441-1-darekm@google.com