irq_work, ppc: Fix up arch hooks

Commit e360adbe29 ("irq_work: Add generic hardirq context
callbacks") fouled up the ppc bit, not properly naming the
arch specific function that raises the 'self-IPI'.

Cc: Huang Ying <ying.huang@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Anton Blanchard <anton@samba.org>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: stable@kernel.org # 37+
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-eg0aqien8p1aqvzu9dft6dtv@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/powerpc/kernel/time.c

@@ -544,7 +544,7 @@ DEFINE_PER_CPU(u8, irq_work_pending);
 
 #endif /* 32 vs 64 bit */
 
-void set_irq_work_pending(void)
+void arch_irq_work_raise(void)
 {
 	preempt_disable();
 	set_irq_work_pending_flag();