gpio: loongson-64bit: Switch to dynamic allocate GPIO base in byte mode

gpio: loongson-64bit: Switch to dynamic allocate GPIO base in byte mode

gpiolib want to get completely rid of static gpiobase allocation, so
switch to dynamic allocate GPIO base in byte mode, also can avoid
warning message:

[1.529974] gpio gpiochip0: Static allocation of GPIO base is deprecated,
use dynamic allocation.

Reported-by: Hongliang Wang <wanghongliang@loongson.cn>
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20251023090346.1995894-1-zhoubinbin@loongson.cn
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>