message: storage: fix a bug when checking for hardlink
  Hardlink must be regular files, otherwise directory will be reported
  as hardlink.
diff: @@ -985,7 +985,7 @@ impl RafsV5Inode {
  /// Check whether the inode is a hardlink.
  #[inline]
  pub fn is_hardlink(&self) -> bool {
  - self.i_nlink > 1
  + self.is_reg() && self.i_nlink > 1
  }
  /// Get inode flags
  