powerpc/mpic: Fix irq distribution problem when MPIC_SINGLE_DEST_CPU

For the mpic with a flag MPIC_SINGLE_DEST_CPU, only one bit should be
set in interrupt destination registers.

The code is applicable to 64-bit platforms as well as 32-bit.
Signed-off-by: Zhao Chenhui <chenhui.zhao@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/sysdev/mpic.c

@@ -54,7 +54,7 @@ static DEFINE_RAW_SPINLOCK(mpic_lock);
 
 #ifdef CONFIG_PPC32	/* XXX for now */
 #ifdef CONFIG_IRQ_ALL_CPUS
-#define distribute_irqs	(!(mpic->flags & MPIC_SINGLE_DEST_CPU))
+#define distribute_irqs	(1)
 #else
 #define distribute_irqs	(0)
 #endif
@@ -1703,7 +1703,7 @@ void mpic_setup_this_cpu(void)
 	 * it differently, then we should make sure we also change the default
 	 * values of irq_desc[].affinity in irq.c.
  	 */
-	if (distribute_irqs) {
+	if (distribute_irqs && !(mpic->flags & MPIC_SINGLE_DEST_CPU)) {
 	 	for (i = 0; i < mpic->num_sources ; i++)
 			mpic_irq_write(i, MPIC_INFO(IRQ_DESTINATION),
 				mpic_irq_read(i, MPIC_INFO(IRQ_DESTINATION)) | msk);