AO pull register definition is inverted between pull (up/down) and
pull enable. Fixing this allows to properly apply bias setting
through pinconf

Fixes: 468c234f ("pinctrl: amlogic: Add support for Amlogic Meson GXBB SoC")
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>