Simplify function signature

Signed-off-by: Dennis Chen <barracks510@gmail.com>

daemon/graphdriver/driver.go

@@ -156,7 +156,7 @@ func getBuiltinDriver(name, home string, options []string, uidMaps, gidMaps []id
 }
 
 // New creates the driver and initializes it at the specified root.
-func New(root string, name string, options []string, uidMaps, gidMaps []idtools.IDMap, pg plugingetter.PluginGetter) (Driver, error) {
+func New(root, name string, options []string, uidMaps, gidMaps []idtools.IDMap, pg plugingetter.PluginGetter) (Driver, error) {
 	if name != "" {
 		logrus.Debugf("[graphdriver] trying provided driver: %s", name) // so the logs show specified driver
 		return GetDriver(name, root, options, uidMaps, gidMaps, pg)