irqchip: keystone: Add irq controller ip driver

irqchip: keystone: Add irq controller ip driver

On Keystone SOCs, DSP cores can send interrupts to ARM
host using the IRQ controller IP. It provides 28 IRQ
signals to ARM. The IRQ handler running on HOST OS can
identify DSP signal source by analyzing SRCCx bits in
IPCARx registers. This is one of the component used by
the IPC mechanism used on Keystone SOCs.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Link: https://lkml.kernel.org/r/1406126430-9978-1-git-send-email-grygorii.strashko@ti.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>