Convert Broadcom Kona family GPIO controller bindings to DT schema.

Changes during conversion:
  - add used, but previously undocumented SoC-specific compatibles
Signed-off-by: Stanislav Jakubek <stano.jakubek@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>