refactor and remove unused code

agent/cmd/args.go

@@ -9,8 +9,7 @@ type agentCommandValidator struct{}
 
 func (v agentCommandValidator) IsCommandValid(cmd string) bool {
 	switch cmd {
-	case CommandStart,
-		CommandNewClient:
+	case CommandStart, CommandNewClient:
 		return true
 	}
 	return false

agent/cmd/main.go

@@ -72,8 +72,7 @@ func main() {
 		E.LogFatal("init CA error", err)
 	}
 
-	switch args.Command {
-	case CommandNewClient:
+	if args.Command == CommandNewClient {
 		printNewClientHelp(ca)
 		return
 	}