pinctrl: uniphier: Add another audio I/O pin-mux settings for LD20

pinctrl: uniphier: Add another audio I/O pin-mux settings for LD20

This adds support for pinmux settings of aout1b group. This group includes
audio I/O signals derived from xirq pins, and it is equivalent to "aout1"
in functionality.

Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Link: https://lore.kernel.org/r/1564465410-9165-3-git-send-email-hayashi.kunihiko@socionext.com
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>