drm/bridge: dw-hdmi: add cec notifier support

Add CEC notifier support to the HDMI bridge driver, so that the CEC
part of the IP can receive its physical address.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Tested-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: https://patchwork.freedesktop.org/patch/msgid/E1dcBhV-00088e-8x@rmk-PC.armlinux.org.uk