[SPARC64]: More fully work around Spitfire Errata 51.

It appears that a memory barrier soon after a mispredicted
branch, not just in the delay slot, can cause the hang
condition of this cpu errata.

So move them out-of-line, and explicitly put them into
a "branch always, predict taken" delay slot which should
fully kill this problem.

Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc64/kernel/process.c

@@ -103,7 +103,7 @@ void cpu_idle(void)
 		 * other cpus see our increasing idleness for the buddy
 		 * redistribution algorithm.  -DaveM
 		 */
-		membar("#StoreStore | #StoreLoad");
+		membar_storeload_storestore();
 	}
 }