ath9k: make NF load complete quickly and reliably

Make NF load complete quickly and reliably. NF load execution
is delayed by HW to end of frame if frame Rx or Tx is ongoing.
Increasing timeout to max frame duration. If NF cal is ongoing
before NF load, stop it before load, and restart it afterwards.

Signed-off-by: Miaoqing Pan <miaoqing@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>