mutex: Avoid label warning when !CONFIG_MUTEX_SPIN_ON_OWNER

Fengguang reported the following warning when optimistic
spinning is disabled (ie: make allnoconfig):

   kernel/mutex.c:599:1: warning: label 'done' defined but not used

Remove the 'done' label altogether.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/mutex.c

@@ -489,7 +489,8 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
 
 			mutex_set_owner(lock);
 			mspin_unlock(MLOCK(lock), &node);
-			goto done;
+			preempt_enable();
+			return 0;
 		}
 		mspin_unlock(MLOCK(lock), &node);
 
@@ -596,7 +597,6 @@ skip_wait:
 	}
 
 	spin_unlock_mutex(&lock->wait_lock, flags);
-done:
 	preempt_enable();
 	return 0;