sparc64: smp_callin: Enable irqs after preemption is disabled

Most of other architectures have below suggested order.
So lets do the same to fit generic idle loop scheme better.
Signed-off-by: NKirill Tkhai <tkhai@yandex.ru>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

arch/sparc/kernel/smp_64.c

@@ -123,11 +123,12 @@ void smp_callin(void)
 		rmb();
 
 	set_cpu_online(cpuid, true);
-	local_irq_enable();
 
 	/* idle thread is expected to have preempt disabled */
 	preempt_disable();
 
+	local_irq_enable();
+
 	cpu_startup_entry(CPUHP_ONLINE);
 }