arm64: only select PINCTRL for Allwinner platforms

As the pinctrl driver selecting is refactored in Kconfig file of
pinctrl-sunxi, now we can select only PINCTRL for Allwinner platform,
and the default value of several pinctrl drivers useful on ARM64
Allwinner SoCs will become Y.

This is the situation of 32-bit ARM ARCH_SUNXI option.

Drop the select of per-SoC pinctrl choices, but keep selecting PINCTRL.

Signed-off-by: Icenowy Zheng <icenowy@aosc.xyz>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>