pinctrl: meson: fix pinconf bias disable

If a bias is enabled on a pin of an Amlogic SoC, calling .pin_config_set()
with PIN_CONFIG_BIAS_DISABLE will not disable the bias. Instead it will
force a pull-down bias on the pin.

Instead of the pull type register bank, the driver should access the pull
enable register bank.

Fixes: 6ac73095 ("pinctrl: add driver for Amlogic Meson SoCs")
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>