dts: riscv: spacemit: k3: Fix I/O power settings

dts: riscv: spacemit: k3: Fix I/O power settings

SpacemiT K3 SoC support dual-voltage I/O power domain, while initially
configure to 3.3v, and need to access register from APBC space to switch
to 1.8v domain.

Fix the GMAC0's I/O pins 1.8v switch failure that will result a broken
ethernet driver.

Fixes: d8944577496b ("riscv: dts: spacemit: k3: add pinctrl support")
Reported-by: Han Gao <gaohan@iscas.ac.cn>
Link: https://patch.msgid.link/20260518-07-dts-pinctrl-io-power-v1-1-abe19c14a726@kernel.org
Signed-off-by: Yixun Lan <dlan@kernel.org>