drm/bridge: add a driver for T-Head TH1520 HDMI controller

drm/bridge: add a driver for T-Head TH1520 HDMI controller

T-Head TH1520 SoC contains a Synopsys DesignWare HDMI controller (paired
with DesignWare HDMI TX PHY Gen2) that takes the "DP" output from the
display controller.

Add a driver for this controller utilizing the common DesignWare HDMI
code in the kernel.

Signed-off-by: Icenowy Zheng <uwu@icenowy.me>
Signed-off-by: Icenowy Zheng <zhengxingda@iscas.ac.cn>
Tested-by: Han Gao <gaohan@iscas.ac.cn>
Tested-by: Michal Wilczynski <m.wilczynski@samsung.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patch.msgid.link/20260129023922.1527729-6-zhengxingda@iscas.ac.cn