pinctrl: sunxi: Enable the pinctrl Kconfig options by default

Enable the freshly introduced Kconfig options whenever their matching
architecture is enabled.

Since the Kconfig symbols for these machines are going through a different
tree, keep PINCTRL_SUNXI around for the moment to avoid breaking the defconfig.
It should be removed eventually.

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