pinctrl: uniphier: rename CONFIG options and file names

The current "CONFIG_PINCTRL_UNIPHIER_PH1_*" is too long.  It would
not hurt to drop "PH1_" because "UNIPHIER_" already well specifies
the SoC family.  Also, rename files for consistency.

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