dt-bindings: auxdisplay: ht16k33: Convert to json-schema

Convert the Holtek HT16K33 LED controller with keyscan Device Tree
binding documentation to json-schema.

Move the file from display to auxdisplay.
Update the example:
  - Sort properties in order of documentation,
  - Group tuples using angle brackets to improve human readability and
    enable automatic validation.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Robin van der Gracht <robin@protonic.nl>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>