Workaround for QEMU ppc 32 to force interrupt acknoledgement

signed-off-by: Jason Wessel <jason.wessel@windriver.com>

Index: linux-2.6.21-rc1/kernel/irq/chip.c
===================================================================
--- linux-2.6.21-rc1.orig/kernel/irq/chip.c
+++ linux-2.6.21-rc1/kernel/irq/chip.c
@@ -225,11 +225,17 @@ static void default_enable(unsigned int 
 	desc->status &= ~IRQ_MASKED;
 }
 
+#define IRQ_DELAYED_DISABLE    0x10000000      /* IRQ disable (masking) happens delayed. */
+
 /*
  * default disable function
  */
 static void default_disable(unsigned int irq)
 {
+	struct irq_desc *desc = irq_desc + irq;
+
+	if (!(desc->status & IRQ_DELAYED_DISABLE))
+		desc->chip->mask(irq);
 }
 
 /*