dt-bindings: display: ili9341: document canaan kd233's lcd

The Canaan KD233 development board has a built in LCD.
Add a specific compatible for it.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20220705215213.1802496-3-mail@conchuod.ie


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>