pinctrl: ingenic: Add ingenic,jz4725b-gpio compatible string

Add a compatible string to support the GPIO chips on the JZ4725B SoC.
There was already a compatible string for the pinctrl node, but not for
the individual GPIO chip nodes.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20200612120609.12730-1-paul@crapouillou.net


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