dt-bindings: display: Add SSD132x OLED controllers

Add a Device Tree binding schema for the OLED panels based on the Solomon
SSD132x family of controllers.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20231014071520.1342189-7-javierm@redhat.com