MLStorage: fix double sd appearing

Checking to see if the directory is readable removes the wrong sd card

application/vlc-android/src/org/videolan/vlc/providers/StorageProvider.kt

@@ -45,7 +45,8 @@ class StorageProvider(context: Context, dataset: LiveDataset<MediaLibraryItem>,
         var storage: Storage
         val storagesList = ArrayList<MediaLibraryItem>()
         for (mediaDirLocation in storages) {
-            if (!File(mediaDirLocation).exists()) continue
+            val file = File(mediaDirLocation)
+            if (!file.exists() || !file.canRead()) continue
             if (mediaDirLocation.isEmpty()) continue
             storage = Storage(Uri.fromFile(File(mediaDirLocation)))
             if (AndroidDevices.EXTERNAL_PUBLIC_DIRECTORY == mediaDirLocation)