boot hang on multi-quad machines.

As mentioned in several posts, the balance_irq code introduced in 2.5.9 is broken for any architecture that doesn't use flat logical addressing. Also, even when it does work, there have been several reports of it degrading performance. As the NUMA-Q architecture I work with doesn't use flat logical addressing, and it isn't worth the possible performance hit, I'm submitting this patch for inclusion into the mainline.

Cheers!

-Matt

@@ -247,7 +247,7 @@
 
 static inline void balance_irq(int irq)
 {
-#if CONFIG_SMP
+#if (CONFIG_SMP && !CONFIG_MULTIQUAD)
 	irq_balance_t *entry = irq_balance + irq;
 	unsigned long now = jiffies;