ath10k: fix protected flag stripping

This prevents protected flag being stripped from
undecrypted raw sniffed frames when monitor
interface is active.

Reported-by: Chun-Yeow Yeoh <yeohchunyeow@gmail.com>
Tested-by: Chun-Yeow Yeoh <yeohchunyeow@gmail.com>
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>