drm/bridge: dw-hdmi-qp: Add CEC support

drm/bridge: dw-hdmi-qp: Add CEC support

Add support for the CEC interface of the Synopsys DesignWare HDMI QP TX
controller.

This is based on the downstream implementation, but rewritten on top of
the CEC helpers added recently to the DRM HDMI connector framework.

Also note struct dw_hdmi_qp_plat_data has been extended to include the
CEC IRQ number to be provided by the platform driver.

Co-developed-by: Algea Cao <algea.cao@rock-chips.com>
Signed-off-by: Algea Cao <algea.cao@rock-chips.com>
Co-developed-by: Derek Foreman <derek.foreman@collabora.com>
Signed-off-by: Derek Foreman <derek.foreman@collabora.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20250903-rk3588-hdmi-cec-v4-1-fa25163c4b08@collabora.com