dt-bindings: display/bridge: add binding for TH1520 HDMI controller

dt-bindings: display/bridge: add binding for TH1520 HDMI controller

T-Head TH1520 SoC contains a Synopsys DesignWare HDMI controller paired
with DesignWare HDMI PHY, with an extra clock gate for HDMI pixel clock
and two reset controls.

Add a device tree binding to it.

Signed-off-by: Icenowy Zheng <uwu@icenowy.me>
Signed-off-by: Icenowy Zheng <zhengxingda@iscas.ac.cn>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patch.msgid.link/20260129023922.1527729-5-zhengxingda@iscas.ac.cn