locking/atomic, arch/mips: Convert to _relaxed atomics

locking/atomic, arch/mips: Convert to _relaxed atomics

Generic code will construct {,_acquire,_release} versions by adding the
required smp_mb__{before,after}_atomic() calls.

XXX if/when MIPS will start using their new SYNCxx instructions they
can provide custom __atomic_op_{acquire,release}() macros as per the
powerpc example.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>