LinuxKPI: 802.11: cleanup debugging

Cleanup some debugging. Rename the global variable to be less
generic. Hide all debugging behind #ifdef for now and turn off.
Rename the debugging sysctl so we can start adding more to the
subtree.

There is a need to change that wildly grown infrastructure into
something more homogenic soon but this should do for 13.1.

Sponsored by: The FreeBSD Foundation
MFC after: 3 days