[PATCH] powerpc: CPM2 interrupt handler failure after 100,000 interrupts

The CPM2 interrupt handler does not return success to the IRQ subsystem, which
causes it to kill the IRQ line after 100,000 interrupts.

Signed-off-by: Edson Seabra <Edson.Seabra@cyclades.com>
Signed-off-by: Marcelo Tosatti <marcelo.tosatti@cyclades.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>