Update git submodules

* Update charm-cinder from branch 'master'
  to df94221404efcf3a1d58a36913e9f44a0c908444
  - Merge "Retry online_data_migrations until exit code 0 or 2."
  - Retry online_data_migrations until exit code 0 or 2.
    
    The command 'cinder-manage db online_data_migrations' has three possible
    exit codes:
    
    - 0: The migrations have been completed successfully.
    - 1: Some migrations have been completed, but more objects need to be
      migrated.
    - 2: Some migrations are generating errors and manual intervention is
      needed.
    
    This change will run in a loop the command online_data_migrations in
    batches of 5000 objects, when the exit code is 1 runs again, when the
    exit code is 0 the loop is stopped, when the exit code is 2 a
    CalledProcessError exception is raised.
    
    Change-Id: Iee99e9ab9777392f05c1a0db55951d97773bb0ba

charm-cinder

@@ -1 +1 @@
-Subproject commit 6ae6c1beef57e7dc27ba82722a09b3576f50df29
+Subproject commit df94221404efcf3a1d58a36913e9f44a0c908444