MN10300: Make cpu_relax() invoke barrier()

Make cpu_relax() invoke barrier() to be the same as other arches.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/asm-mn10300/processor.h

@@ -58,7 +58,7 @@ extern struct mn10300_cpuinfo boot_cpu_data;
 extern void identify_cpu(struct mn10300_cpuinfo *);
 extern void print_cpu_info(struct mn10300_cpuinfo *);
 extern void dodgy_tsc(void);
-#define cpu_relax() do {} while (0)
+#define cpu_relax() barrier()
 
 /*
  * User space process size: 1.75GB (default).