Revert "pinctrl: sunxi: Don't enforce bias disable (for now)"

This reverts commit 2154d94b

.

The original patch was intented to avoid some issues with the sunxi
gpio rework and was supposed to be reverted after all the required
DT bits had been merged around v4.10.

Signed-off-by: Priit Laes <plaes@plaes.org>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>