dw-hdmi-cec: use cec_notifier_cec_adap_(un)register

Use the new cec_notifier_cec_adap_(un)register() functions to
(un)register the notifier for the CEC adapter.

Also adds CEC_CAP_CONNECTOR_INFO capability to the adapter.

Changes since v3:
	- add CEC_CAP_CONNECTOR_INFO to cec_allocate_adapter,
	- replace CEC_CAP_LOG_ADDRS | CEC_CAP_TRANSMIT |
	CEC_CAP_RC | CEC_CAP_PASSTHROUGH with CEC_CAP_DEFAULTS.

Signed-off-by: Dariusz Marcinkiewicz <darekm@google.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Tested-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190814104520.6001-4-darekm@google.com