P54 devices always generate a full tx_status report
(ACK, PSM, rate control, etc..) for every xmitted frame.

Therefore, I think The driver qualifies for the
REPORTS_TX_ACK_STATUS hardware feature flag.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>