cfg80211: allow the plink state blocking for user managed mesh

wpa_supplicant or authsae handles the mesh peering in user
space, but the plink state is still managed in kernel space.
Currently, there is no implementation by wpa_supplicant or
authsae to block the plink state after it is set to ESTAB.

By applying this patch, we can use the "iw mesh0 station set
<MAC address> plink_action block" to block the peer mesh STA.
This is useful for experimenting purposes.
Signed-off-by: Chun-Yeow Yeoh <yeohchunyeow@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

@@ -4061,7 +4061,8 @@ int cfg80211_check_station_change(struct wiphy *wiphy,
 			return -EINVAL;
 		break;
 	case CFG80211_STA_MESH_PEER_USER:
-		if (params->plink_action != NL80211_PLINK_ACTION_NO_ACTION)
+		if (params->plink_action != NL80211_PLINK_ACTION_NO_ACTION &&
+		    params->plink_action != NL80211_PLINK_ACTION_BLOCK)
 			return -EINVAL;
 		break;
 	}