pinctrl: uniphier: widen all pinconf-derived arguments to u32

Since commit 58957d2e

 ("pinctrl: Widen the generic pinconf argument
from 16 to 24 bits"), the generic pinconf arguments are handled by u32.

UniPhier pinctrl drivers do not support debouncing, so u16 is working,
but align the argument type to u32 for consistency.

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