ath10k: fix QoS tx

Since we have a silly FW workaround we must
extract the tid *before* we apply the workaround.
Otherwise we cut out QoS Control field containing
the tid so it can't be accessed later on from
inside the tx frame.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>