support the new iwx SCD_QUEUE_CONFIG command

support the new iwx SCD_QUEUE_CONFIG command

Required for adding/removing Tx queues on new firmware versions.

Semantics have changed yet again. Good old iwm(4) required manual
removal of related Tx queues when a station is removed from firmware.
At some point iwx(4) firmware removed this requirement and demanded
that queue removal would be done implicitly by firmware instead.
And now the firmware engineers at Intel have again changed their
minds about this, and explicit queue removal is required again.
It is sad that we are being driven through such a marathon of changes
just in order to pick up some firmware security fixes...