The RTL8231 auxiliary controller is not defined in the rtl931x.dtsi.
Additionally the pinmux is configured at the wrong address. Fix
this.
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/19776
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>