drm/tegra: hdmi: Add cec-notifier support

In order to support CEC the HDMI driver has to inform the CEC driver
whenever the physical address changes. So when the EDID is read the
CEC driver has to be informed and whenever the hotplug detect goes
away.

This is done through the cec-notifier framework.

The link between the HDMI driver and the CEC driver is done through
the hdmi-phandle property in the tegra-cec node in the device tree.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>