gpio: loongson-64bit: Correct Loongson-7A2000 ACPI GPIO access mode

According to the description of the Loongson-7A2000 ACPI GPIO register in
the manual, its access mode should be BIT_CTRL_MODE, otherwise there maybe
some unpredictable behavior.

Cc: stable@vger.kernel.org
Fixes: 44fe7902 ("gpio: loongson-64bit: Add more gpio chip support")
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Link: https://lore.kernel.org/r/20250610115926.347845-1-zhoubinbin@loongson.cn


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