irq_work, ppc: Fix up arch hooks

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 <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Anton Blanchard <[email protected]>
Cc: Eric B Munson <[email protected]>
Cc: [email protected] # 37+
Signed-off-by: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/n/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>