dt-bindings: gpio: loongson: Add new loongson gpio chip compatible

Add the devicetree compatibles for Loongson-7A2000 and Loongson-3A6000
gpio chip.

Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Huacai Chen <chenhuacai@loongson.cn>
Link: https://lore.kernel.org/r/20250303074552.3335186-1-zhoubinbin@loongson.cn


Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>