Fix the driver name empty case

As drivername maybe "" in hostconfig, so we should not
directly print dirvername with var drivername,
instead, we use the real driver name property to print it.

Fixes: #20900
Signed-off-by: Kai Qiang Wu(Kennan) <wkqwu@cn.ibm.com>

volume/store/store.go

@@ -194,12 +194,14 @@ func (s *VolumeStore) create(name, driverName string, opts map[string]string) (v
 		}
 	}
 
-	logrus.Debugf("Registering new volume reference: driver %q, name %q", driverName, name)
 	vd, err := volumedrivers.GetDriver(driverName)
+
 	if err != nil {
 		return nil, &OpErr{Op: "create", Name: name, Err: err}
 	}
 
+	logrus.Debugf("Registering new volume reference: driver %q, name %q", vd.Name(), name)
+
 	if v, _ := vd.Get(name); v != nil {
 		return v, nil
 	}