Adding OpenWrt support for Xiaomi AX3600 (Part 1)

I can trigger this reliably (started testing with the last 2/3 snapshots published in July) by putting select SSIDs on both of the ath11k radios; I know if I swap one of them from the 2.4 ath11k with the 2.4 ath10k it doesn't seem to happen. Has anyone looked closer into all this?