dt-bindings: display: Split common Solomon properties in their own schema

There are DT properties that can be shared across different Solomon OLED
Display Controller families. Split them into a separate common schema to
avoid these properties to be duplicated in different DT bindings schemas.

Suggested-by: Rob Herring <robh@kernel.org>
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/20231014071520.1342189-6-javierm@redhat.com