irqchip: Devicetree: document Conexant Digicolor irq binding

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Link: http://lkml.kernel.org/r/505a65c8861e5210d94227bc0eec89cab0593fca.1421317616.git.baruch@tkos.co.il


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>