DT: omap4/5: add binding for the wake-up generator

Add a binding for the OMAP4/5 wake-up generator, which acts as
an interrupt controller feeding into the GIC.

Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/1426088629-15377-7-git-send-email-marc.zyngier@arm.com


Signed-off-by: Jason Cooper <jason@lakedaemon.net>