Add support for the sh7377 INTCS interrupt controller.

INTCS is the interrupt controller for the sh7377 SuperH
processor core. It is tied into the INTCA interrupt
controller which interfaces to the ARM processor.

INTCS support is implemented using a new INTC table
together with a chained interrupt handler that ties
into the already supported INTCA controller.
Signed-off-by: Kuninori Morimoto <morimoto.kuninori@renesas.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>