[POWERPC] cell: Add routines for managing PMU interrupts

The following routines are added to arch/powerpc/platforms/cell/pmu.c:
 cbe_clear_pm_interrupts()
 cbe_enable_pm_interrupts()
 cbe_disable_pm_interrupts()
 cbe_query_pm_interrupts()
 cbe_pm_irq()
 cbe_init_pm_irq()

This also adds a routine in arch/powerpc/platforms/cell/interrupt.c and
some macros in cbe_regs.h to manipulate the IIC_IR register:
 iic_set_interrupt_routing()

Signed-off-by: Kevin Corry <kevcorry@us.ibm.com>
Signed-off-by: Carl Love <carll@us.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>