[XTENSA] Initialize semaphore_wake_lock

Initialize semaphore_wake_lock.
Signed-off-by: NChris Zankel <chris@zankel.net>

arch/xtensa/kernel/semaphore.c

@@ -100,7 +100,7 @@ static __inline__ int waking_non_zero_trylock(struct semaphore *sem)
 	return ret;
 }
 
-spinlock_t semaphore_wake_lock;
+DEFINE_SPINLOCK(semaphore_wake_lock);
 
 /*
  * Semaphores are implemented using a two-way counter: