Fixes multiple files behavior in files rootfs

Some files may be left uncopied to the VM when there are multiple
files in the .minikube/files directory as the code misinterprets
the last parent dir as parent dirs for all files, which results
some files with the same name were not copied.

This patch fixes the behavior.

pkg/minikube/assets/addons.go

@@ -302,14 +302,15 @@ func addMinikubeDirToAssets(basedir, vmpath string, assets *[]CopyableFile) erro
 			return errors.Wrapf(err, "checking if %s is directory", hostpath)
 		}
 		if !isDir {
-			if vmpath == "" {
+			vmdir := vmpath
+			if vmdir == "" {
 				rPath, err := filepath.Rel(basedir, hostpath)
 				if err != nil {
 					return errors.Wrap(err, "generating relative path")
 				}
 				rPath = filepath.Dir(rPath)
 				rPath = filepath.ToSlash(rPath)
-				vmpath = path.Join("/", rPath)
+				vmdir = path.Join("/", rPath)
 			}
 			permString := fmt.Sprintf("%o", info.Mode().Perm())
 			// The conversion will strip the leading 0 if present, so add it back
@@ -318,7 +319,7 @@ func addMinikubeDirToAssets(basedir, vmpath string, assets *[]CopyableFile) erro
 				permString = fmt.Sprintf("0%s", permString)
 			}
 
-			f, err := NewFileAsset(hostpath, vmpath, filepath.Base(hostpath), permString)
+			f, err := NewFileAsset(hostpath, vmdir, filepath.Base(hostpath), permString)
 			if err != nil {
 				return errors.Wrapf(err, "creating file asset for %s", hostpath)
 			}