Remove redundant os.Stat call, use os.ReadDir error directly

ReadDir already returns os.ErrNotExist when the directory does not
exist, so no need to run Stat before ReadDir.

Signed-off-by: chijiajian <33536362+chijiajian@users.noreply.github.com>

Author: ZStack-Robot

sysfs/class_fibrechannel.go

@@ -152,20 +152,15 @@ func parseFibreChannelStatistics(hostPath string) (*FibreChannelCounters, error)
 	var counters FibreChannelCounters
 
 	path := filepath.Join(hostPath, "statistics")
-
-	if _, err := os.Stat(path); err != nil {
+	files, err := os.ReadDir(path)
+	if err != nil {
 		if errors.Is(err, os.ErrNotExist) {
 			// statistics directory not present, skip
 			return &counters, nil
 		}
 		return nil, err
 	}
 
-	files, err := os.ReadDir(path)
-	if err != nil {
-		return nil, err
-	}
-
 	for _, f := range files {
 		if !f.Type().IsRegular() || f.Name() == "reset_statistics" {
 			continue