Move 'path' package usage to 'path/filepath'.

In case of windows, the path package functions such as 'Dir' returns faulty directory path.
For eg: 'path.Dir' on 'c:\var\lib\kubelet\pods' returns '.', where as the result should
have been 'c:\var\lib\kubelet'. The filepath package returns the right values.

pkg/volume/csi/csi_mounter.go

@@ -22,7 +22,6 @@ import (
 	"errors"
 	"fmt"
 	"os"
-	"path"
 	"path/filepath"
 	"strconv"
 
@@ -432,7 +431,7 @@ func removeMountDir(plug *csiPlugin, mountPath string) error {
 			return errors.New(log("failed to remove dir [%s]: %v", mountPath, err))
 		}
 		// remove volume data file as well
-		volPath := path.Dir(mountPath)
+		volPath := filepath.Dir(mountPath)
 		dataFile := filepath.Join(volPath, volDataFileName)
 		klog.V(4).Info(log("also deleting volume info data file [%s]", dataFile))
 		if err := os.Remove(dataFile); err != nil && !os.IsNotExist(err) {

pkg/volume/csi/csi_plugin.go

@@ -20,7 +20,7 @@ import (
 	"errors"
 	"fmt"
 	"os"
-	"path"
+	"path/filepath"
 	"strings"
 	"time"
 
@@ -387,7 +387,7 @@ func (p *csiPlugin) NewMounter(
 
 	// Save volume info in pod dir
 	dir := mounter.GetPath()
-	dataDir := path.Dir(dir) // dropoff /mount at end
+	dataDir := filepath.Dir(dir) // dropoff /mount at end
 
 	if err := os.MkdirAll(dataDir, 0750); err != nil {
 		return nil, errors.New(log("failed to create dir %#v:  %v", dataDir, err))
@@ -438,7 +438,7 @@ func (p *csiPlugin) NewUnmounter(specName string, podUID types.UID) (volume.Unmo
 
 	// load volume info from file
 	dir := unmounter.GetPath()
-	dataDir := path.Dir(dir) // dropoff /mount at end
+	dataDir := filepath.Dir(dir) // dropoff /mount at end
 	data, err := loadVolumeData(dataDir, volDataFileName)
 	if err != nil {
 		return nil, errors.New(log("unmounter failed to load volume data file [%s]: %v", dir, err))