[net80211] add another hard-learnt lesson about DWDS setup

wlanwds monitors the physical interface for DWDS requests from VAPs,
but the clone is created against the physical interface. So, if you
have a secondary VAP setup (with a separate, non-physical-default MAC
address) which is configured for DWDS, the temporary DWDS VAPs created
will have the MAC of the parent physical interface and NOT the
actual cloned interface + MAC.

This .. stumped me for a few minutes.

Maybe I'll fix it. Maybe I won't. At least I now have DWDS+encryption
working at home.

Tested:

• yes, with DWDS 11n repeaters now working on freebsd.