dt-bindings: display: add verisilicon,dc

dt-bindings: display: add verisilicon,dc

Verisilicon has a series of display controllers prefixed with DC and
with self-identification facility like their GC series GPUs.

Add a device tree binding for it.

Depends on the specific DC model, it can have either one or two display
outputs, and each display output could be set to DPI signal or "DP"
signal (which seems to be some plain parallel bus to HDMI controllers).

Signed-off-by: Icenowy Zheng <uwu@icenowy.me>
Signed-off-by: Icenowy Zheng <zhengxingda@iscas.ac.cn>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patch.msgid.link/20260129023922.1527729-3-zhengxingda@iscas.ac.cn