Device-Tree bindings for tegra nvavp driver

Required properties:
- compatible: value should be "nvidia,tegra114-nvavp"/"nvidia,tegra124-nvavp"/"nvidia,tegra30-nvavp"
- reg: physical base address of mailbox, nvavp vector table
- interrupts: interrupt number to the cpu.

Note: nvavp should is child of the host1x
Example:
	nvavp {
		compatible = "nvidia,tegra114-nvavp";
		interrupts = <0 4 0x04>; /* mailbox AVP IRQ */
		reg = <0x60001000 0x0000e200>;
	};