arch,openrisc: Convert smp_mb__*()

Openrisc fully relies on asm-generic/barrier.h and therefore its
smp_mb() is barrier().
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/n/tip-sxgxgqag9tond4kji07d22oh@git.kernel.org
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Cc: linux@lists.openrisc.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/openrisc/include/asm/bitops.h

@@ -27,14 +27,7 @@
 
 #include <linux/irqflags.h>
 #include <linux/compiler.h>
-
-/*
- * clear_bit may not imply a memory barrier
- */
-#ifndef smp_mb__before_clear_bit
-#define smp_mb__before_clear_bit()	smp_mb()
-#define smp_mb__after_clear_bit()	smp_mb()
-#endif
+#include <asm/barrier.h>
 
 #include <asm/bitops/__ffs.h>
 #include <asm-generic/bitops/ffz.h>