gpio: loongson-64bit: Extend GPIO irq support

gpio: loongson-64bit: Extend GPIO irq support

Add the interrupt enable register offset (inten_offset) so that GPIO
interrupts can be enabled normally on more models.

According to the latest interface specifications, the definition of GPIO
interrupts in ACPI is similar to that in FDT. The GPIO interrupts are
listed one by one according to the GPIO number, and the corresponding
interrupt number can be obtained directly through the GPIO number
specified by the consumer.

Signed-off-by: Xi Ruoyao <xry111@xry111.site>
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Link: https://lore.kernel.org/r/20250714064542.2276247-1-zhoubinbin@loongson.cn
[Bartosz: tweaked the commit message]
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>