ath10k: fix group privacy action frame decryption for qca4019

Recent commit 46f6b060 ("mac80211: Encrypt "Group addressed privacy" action
frames") encrypts group privacy action frames. But qca99x0 family chipset
delivers broadcast/multicast management frames as encrypted and it should be
decrypted by mac80211. Setting RX_FLAG_DECRYPTED stats for those frames is
breaking mesh connection establishment.

Signed-off-by: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>