tracing/kmemtrace: fix typo

Impact: build fix
Signed-off-by: Ingo Molnar <mingo@elte.hu>

mm/slab.c

@@ -102,7 +102,7 @@
 #include	<linux/cpu.h>
 #include	<linux/sysctl.h>
 #include	<linux/module.h>
-#include	<tracing/kmemtrace.h>
+#include	<trace/kmemtrace.h>
 #include	<linux/rcupdate.h>
 #include	<linux/string.h>
 #include	<linux/uaccess.h>