dt-bindings: display: ssd132x: Add vendor prefix to width and height

Commit 2d23e7d6 ("dt-bindings: display: Add SSD132x OLED controllers")
used the wrong properties for width and height, instead of the correct
"solomon,width" and "solomon,height" properties.

Fix this by adding the vendor prefix to the width and height properties.

Fixes: 2d23e7d6

 ("dt-bindings: display: Add SSD132x OLED controllers")
Reported-by: Conor Dooley <conor@kernel.org>
Closes: https://lore.kernel.org/dri-devel/20231218-example-envision-b41ca8efa251@spud/
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231229112026.2797483-3-javierm@redhat.com