delete useless code

Signed-off-by: ningmingxiao <ning.mingxiao@zte.com.cn>

cmd/containerd-stress/density.go

@@ -75,9 +75,6 @@ var densityCommand = cli.Command{
 		s := make(chan os.Signal, 1)
 		signal.Notify(s, syscall.SIGTERM, syscall.SIGINT)
 
-		if err != nil {
-			return err
-		}
 		var (
 			pids  []uint32
 			count = cliContext.Int("count")