pinctrl: remove redundant if conditional from Kconfig

The whole menu is guarded by

  menu "Pin controllers"
          depends on PINCTRL
      ...
  endmenu

The if conditional outside of it is redundant.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>