Power Management: use mutexes instead of semaphores

The Power Management code uses semaphores as mutexes.  Use the mutex API
instead of the (binary) semaphores.

Signed-off-by: Matthias Kaehlcke <matthias.kaehlcke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/base/power/power.h

@@ -14,12 +14,12 @@ extern void device_shutdown(void);
 /*
  * Used to synchronize global power management operations.
  */
-extern struct semaphore dpm_sem;
+extern struct mutex dpm_mtx;
 
 /*
  * Used to serialize changes to the dpm_* lists.
  */
-extern struct semaphore dpm_list_sem;
+extern struct mutex dpm_list_mtx;
 
 /*
  * The PM lists.