sparc64: Fix UP build.

Can't reference irq_desc[].affinity when !SMP.

Reported-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/kernel/irq_64.c

@@ -268,10 +268,8 @@ static int irq_choose_cpu(unsigned int virt_irq, const struct cpumask *affinity)
 	return cpuid;
 }
 #else
-static int irq_choose_cpu(unsigned int virt_irq, const struct cpumask *affinity)
-{
-	return real_hard_smp_processor_id();
-}
+#define irq_choose_cpu(virt_irq, affinity)	\
+	real_hard_smp_processor_id()
 #endif
 
 static void sun4u_irq_enable(unsigned int virt_irq)