The spec requires to decrement the CSA counters based on TBTT,
regardless if the beacon was actually transmitted. Previously, the fw
would send beacon notifications only for successfully transmitted
beacons. This behavior resulted in inaccurate CSA countdown. In order
to address this issue, the fw was changed to send beacon
notifications also for not transmitted beacons. Such notifications
have TX_STATUS_INTERNAL_ABORT (0x92).
Don't start the CSA countdown before first successfully transmitted
beacon, in order to guarantee that the CSA is announced for a
required period.
Signed-off-by: Andrei Otcheretianski <andrei.otcheretianski@intel.com>