Open Multi-Processor Interrupt Controller

Required properties:

- compatible : This should be "openrisc,ompic"
- reg : Specifies base physical address and size of the register space. The
  size is based on the number of cores the controller has been configured
  to handle, this should be set to 8 bytes per cpu core.
- interrupt-controller : Identifies the node as an interrupt controller.
- #interrupt-cells : This should be set to 0 as this will not be an irq
  parent.
- interrupts : Specifies the interrupt line to which the ompic is wired.

Example:

ompic: interrupt-controller@98000000 {
	compatible = "openrisc,ompic";
	reg = <0x98000000 16>;
	interrupt-controller;
	#interrupt-cells = <0>;
	interrupts = <1>;
};
