powerpc: define __ARCH_IRQ_EXIT_IRQS_DISABLED

powerpc calls irq_exit() with local irqs disabled, therefore it
can define __ARCH_IRQ_EXIT_IRQS_DISABLED.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/hardirq.h

@@ -29,6 +29,7 @@ DECLARE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
 #define local_softirq_pending()	__this_cpu_read(irq_stat.__softirq_pending)
 
 #define __ARCH_SET_SOFTIRQ_PENDING
+#define __ARCH_IRQ_EXIT_IRQS_DISABLED
 
 #define set_softirq_pending(x) __this_cpu_write(irq_stat.__softirq_pending, (x))
 #define or_softirq_pending(x) __this_cpu_or(irq_stat.__softirq_pending, (x))