pinctrl: meson-gxbb: add missing GPIOX_22 pin

GPIOX_22 is declared as a gpio but the id is no present in the pin
table. This hole trigger an error while reading the pingroup debugfs entry

GPIOX_22 is no routed externally. For all we know, it could an internal
pin of SoC

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>