Texas Instruments ION heap declaration binding

Describes heaps and the associated memory. Each child node provides
information about a single heap. Only chunk and carveout heaps are currently
supported. CMA and system heaps are automatically generated when enabled.

Required Properties:
 - compatible:		Must be "ti,ion"

Required child node properties:
 - memory-region:	A phandle to the reserved memory node that backs this
			heap. The reserved memory node can be a CMA memory
			node, and should be defined as per the bindings in
			Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt

 - ion-heap-type:	Heap type ID as defined by uapi/ion.h

Required child node properties for chunk heaps:
 - ion-chunk-size:	Size of each allocation pool, allocation will only
			be made in granules of this size to prevent
			fragmentation

Example:

ion {
	compatible = "ti,ion";
	ti_chunk_heap_0 {
		memory-region = <&ion_block_mem_0>;
		ion-heap-type = <3>; // ION_HEAP_TYPE_CHUNK
		ion-chunk-size = <0x00010000>; // 64KB
	};

	ti_carveout_heap_0 {
		memory-region = <&ion_block_mem_1>;
		ion-heap-type = <2>; // ION_HEAP_TYPE_CARVEOUT
	};
};
