iwlwifi: mvm: silently drop encrypted frames for unknown station

When a station is removed, the driver-mac80211 station mapping is removed
before the station is actually deleted from the FW. As a result, it is
reasonable that the FW will continue to pass frames although the driver
doesn't have a station for them anymore. Thus change the message
severity level from ERR to DEBUG_DROP.
Signed-off-by: Avraham Stern <avraham.stern@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20210805130823.a751177743c6.I5607504dade88ba461508643f58390dd661c05ba@changeidSigned-off-by: Luca Coelho <luciano.coelho@intel.com>

drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c

@@ -69,8 +69,8 @@ static inline int iwl_mvm_check_pn(struct iwl_mvm *mvm, struct sk_buff *skb,
 
 	/* if we are here - this for sure is either CCMP or GCMP */
 	if (IS_ERR_OR_NULL(sta)) {
-		IWL_ERR(mvm,
-			"expected hw-decrypted unicast frame for station\n");
+		IWL_DEBUG_DROP(mvm,
+			       "expected hw-decrypted unicast frame for station\n");
 		return -1;
 	}