Report PHY of each packet to the host

It's useful info that's not always obvious.
Not yet recording it in pcap as the Wireshark dissector may need updating.

Tweak AUX_OFF_TARG_USEC

Improves reliability of aux advertisement capture from 80% to near 100%.
The latency has to account for radio shutdown, multiple context switches
on the main CPU, RF scheduler invocation, OS scheduler invocation, and
radio restart/retune/reconfiguration.