ARM: vic: device tree binding

This adds a device tree binding for the VIC based on the of_irq_init()
support.  This adds an irqdomain to the vic and always registers all
vics in the static vic array rather than for pm only to keep track of
the irq domain.  struct irq_data::hwirq is used where appropriate rather
than runtime masking.

v3:	- include linux/export.h for THIS_MODULE
v2:	- use irq_domain_simple_ops
	- remove stub implementation of vic_of_init for !CONFIG_OF
	- Make VIC select IRQ_DOMAIN

Reviewed-by: Rob Herring <robherring2@gmail.com>
Reviewed-by: Grant Likely <grant.likely@secretlab.ca>
Tested-by: Thomas Abraham <thomas.abraham@linaro.org>
Signed-off-by: Jamie Iles <jamie@jamieiles.com>