Fix Deauth/Disassoc callback handling with test frames

Fix Deauth/Disassoc callback handling with test frames

The Deauth/Disassoc TX status callbacks were ending up kicking the
station entry from kernel driver when test functionality was used to
inject Deauth/Disassoc frames from the AP with the purpose of leaving
the local association in place. Fix this by using STA flags to figure
out whether there was a pending callback for the frame that we need
to act on.

In addition, add forgotten functionality for the Disassoc TX status
callback to match the behavior with Deauth.