drop_monitor: Use correct error code

The error code 'ENOTSUPP' is reserved for use with NFS. Use 'EOPNOTSUPP'
instead.
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/drop_monitor.c

@@ -298,7 +298,7 @@ static int set_all_monitor_traces(int state)
 static int net_dm_cmd_config(struct sk_buff *skb,
 			struct genl_info *info)
 {
-	return -ENOTSUPP;
+	return -EOPNOTSUPP;
 }
 
 static int net_dm_cmd_trace(struct sk_buff *skb,
@@ -311,7 +311,7 @@ static int net_dm_cmd_trace(struct sk_buff *skb,
 		return set_all_monitor_traces(TRACE_OFF);
 	}
 
-	return -ENOTSUPP;
+	return -EOPNOTSUPP;
 }
 
 static int dropmon_net_event(struct notifier_block *ev_block,