[POWERPC] Adapt ipic driver to new host_ops interface, add set_irq_type to set IRQ sense

This converts ipic code to Benh's IRQ mods.  For the IPIC, IRQ sense values in the device tree equal those in include/linux/irq.h; that's 8 for low assertion (most internal IRQs on mpc83xx), and 2 for high-to-low change.

spinlocks added to [un]mask, ack operations; default handler and type now set in host_map; and redundant condition check eliminated.

Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
Signed-off-by: Li Yang <leoli@freescale.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>