Simplify version check for port count argument

Might be personal preference, but I think this reads more clearly

builder/virtualbox/common/driver_4_2.go

@@ -25,10 +25,11 @@ func (d *VBox42Driver) CreateSATAController(vmName string, name string, portcoun
 	}
 
 	portCountArg := "--portcount"
-	if strings.HasPrefix(version, "0.") || strings.HasPrefix(version, "1.") || strings.HasPrefix(version, "2.") ||
-		strings.HasPrefix(version, "3.") || strings.HasPrefix(version, "4.0") || strings.HasPrefix(version, "4.1") ||
-		strings.HasPrefix(version, "4.2") {
-		portCountArg = "--sataportcount"
+
+	for _, prefix := range [7]string{"0.", "1.", "2.", "3.", "4.0", "4.1", "4.2"} {
+		if strings.HasPrefix(version, prefix) {
+			portCountArg = "--sataportcount"
+		}
 	}
 
 	command := []string{