irqchip: add nps Internal and external irqchips

Adding EZchip NPS400 support.
Internal interrupts are handled by Multi Thread Manager (MTM)
Once interrupt is serviced MTM is acked for deactivating the interrupt.
External interrupts are handled by MTM as well as at Global Interrupt
Controller (GIC) e.g. serial and network devices.

Signed-off-by: Noam Camus <noamc@ezchip.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Acked-by: Jason Cooper <jason@lakedaemon.net>
Cc: Thomas Gleixner <tglx@linutronix.de>