ath9k: advertise support for active monitor interfaces

Signed-off-by: NFelix Fietkau <nbd@openwrt.org>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/init.c

@@ -778,6 +778,8 @@ void ath9k_set_hw_capab(struct ath_softc *sc, struct ieee80211_hw *hw)
 	if (AR_SREV_9160_10_OR_LATER(sc->sc_ah) || ath9k_modparam_nohwcrypt)
 		hw->flags |= IEEE80211_HW_MFP_CAPABLE;
 
+	hw->wiphy->features |= NL80211_FEATURE_ACTIVE_MONITOR;
+
 	hw->wiphy->interface_modes =
 		BIT(NL80211_IFTYPE_P2P_GO) |
 		BIT(NL80211_IFTYPE_P2P_CLIENT) |