dt-bindings: pinctrl: uniphier: Add NX1 pinctrl binding

Update pinctrl binding document for UniPhier NX1 SoC.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Link: https://lore.kernel.org/r/1633518606-8298-3-git-send-email-hayashi.kunihiko@socionext.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>