mac80211: don't apply flow control on management frames

In some cases (depending on the driver, but it's true e.g. for
iwlwifi) we're using an internal TXQ for management packets,
mostly to simplify the code and to have a place to queue them.
However, it appears that in certain cases we can confuse the
code and management frames are dropped, which is certainly not
what we want.

Short-circuit the processing of management frames. To keep the
impact minimal, only put them on the frags queue and check the
tid == management only for doing that and to skip the airtime
fairness checks, if applicable.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20210319232800.0e876c800866.Id2b66eb5a17f3869b776c39b5ca713272ea09d5d@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>