arch,m32r: Convert smp_mb__*()

M32r uses asm-generic/barrier.h and its smp_mb() is barrier();
therefore we can use the generic versions which default to smp_mb().

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-wh6xljltyvmpy9t0bc80k1fy@git.kernel.org


Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Cc: linux-m32r-ja@ml.linux-m32r.org
Cc: linux-m32r@ml.linux-m32r.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>