pinctrl: meson-axg: fix the range of aobus bank

The GPIOAO bank is range from GPIOAO_0 to GPIOAO_13.

Fixes: 83c56680 ("pinctrl: meson-axg: Add new pinctrl driver for Meson AXG SoC")
Reported-by: Xingyu Chen <xingyu.chen@amlogic.com>
Signed-off-by: Yixun Lan <yixun.lan@amlogic.com>
Acked-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>