pinctrl: uniphier: clean up GPIO port muxing

There are a bunch of GPIO muxing data, but most of them are actually
unneeded because GPIO-to-pin mapping can be specified by "gpio-ranges"
DT properties.

Tables that contain a set of GPIO pins are still needed for the named
mapping by "gpio-ranges-group-names".  This is a much cleaner way for
UniPhier SoC family where GPIO numbers are not straight mapped to pin
numbers.

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