pinctrl: ingenic: jz4730: add pinmux for I2S interface

I2S is used for the sound codec of the Alpha400.

Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Link: https://lore.kernel.org/7e79b16be569fb0f501032b2b6ec726e4a09411f.1740823241.git.hns@goldelico.com


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