Midstream kernel doesn't seem to have support for i2s right now https://github.com/Googulator/linux-rk3588-midstream/blob/midstream/arch/arm64/boot/dts/rockchip/rk3588-rock-5b.dts#L143
The driver was merged on mainline kernel -> https://gitlab.collabora.com/hardware-enablement/rockchip-3588/notes-for-rockchip-3588/-/blob/main/mainline-status.md