dt-bindings: vendor-prefixes: add Diodes

Diodes Incorporated is a manufacturer of application specific standard
products within the discrete, logic, analog, and mixed-signal semiconductor
markets.

https://www.diodes.com/



Signed-off-by: Martyn Welch <martyn.welch@collabora.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>