OK, I re-installed an old snapshot that I downloaded on Oct 12 and everything works again. The working snapshot is r27730-3d7040b7d6.
Luckily, I had a left-over copy on my laptop 
The latest snapshot from today (Oct 17 11:47:59) still does not work. Only phy2 (the 5 GHz radio) is initialised, but not phy0 or phy1.
It seems to me that under /sys/devices/platform/soc/11280000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0 are all files as in the "working" case, but I can't see any ieee80211/phy* dirs.
I hope this helps...