[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>
diff --git a/arch/sparc64/kernel/sbus.c b/arch/sparc64/kernel/sbus.c
index 89f5e01..e09ddf9 100644
--- a/arch/sparc64/kernel/sbus.c
+++ b/arch/sparc64/kernel/sbus.c
@@ -147,7 +147,7 @@
 		if (!limit)
 			break;
 		udelay(1);
-		membar("#LoadLoad");
+		rmb();
 	}
 	if (!limit)
 		printk(KERN_WARNING "sbus_strbuf_flush: flushflag timeout "