gpio: loongson-64bit: Add support for Loongson-2K0300 SoC

gpio: loongson-64bit: Add support for Loongson-2K0300 SoC

This controller's input and output logic is similar to previous
generations of SoCs. Additionally, it's capable of interrupt masking,
and could be configured to detect levels and edges, and is supplied with
a distinct reset signal.

The interrupt functionality is implemented through an irqchip, whose
operations are written with previous generation SoCs in mind and could
be reused. Since all Loongson SoCs with similar interrupt capability
(LS2K1500, LS2K2000) support byte-control mode, these operations are for
byte-control mode only for simplicity.

Signed-off-by: Yao Zi <ziyao@disroot.org>
Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250904013438.2405-3-ziyao@disroot.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>