lockdep: Actually _dec_ in debug_atomic_dec

Fix a silly copy-paste mistake that was making debug_atomic_dec use
this_cpu_inc instead of this_cpu_dec.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>

kernel/lockdep_internals.h

@@ -149,7 +149,7 @@ DECLARE_PER_CPU(struct lockdep_stats, lockdep_stats);
 
 #define debug_atomic_dec(ptr)			{		\
 	WARN_ON_ONCE(!irqs_disabled());				\
-	this_cpu_inc(lockdep_stats.ptr);			\
+	this_cpu_dec(lockdep_stats.ptr);			\
 }
 
 #define debug_atomic_read(ptr)		({				\