recovery: Fix the progress bar

 * The progress thread is running all the time, which causes the device
   to heat up while in recovery. Start this thread only when the
   progress mode is set to something other than EMPTY, and add a
   terminating condition so that it exits when finished.

 * Incorporate Tom's patch to keep it updated when visible, since
   both are needed to get working progress indications without
   killing batteries.

 * Clear buffer in draw_progress_locked() and always call this in
   update_progress_locked().  This is necessary to ensure that all
   backing frames in the graphics implementation get updated because
   we aren't guaranteed to have any particular number of backing
   frames.

 * Remove dialogs on wipe operations since we are using the progress
   animation now.

 * Set progress indicator after showing "Formatting" text to avoid
   momentary flicker.

Change-Id: Ib70d2cb25f01d9920ffb698b5b5b47af827ef483