* Marvell XOR engines

Required properties:
- compatible: Should be one of the following:
  - "marvell,orion-xor"
  - "marvell,armada-380-xor"
  - "marvell,armada-3700-xor".
- reg: Should contain registers location and length (two sets)
    the first set is the low registers, the second set the high
    registers for the XOR engine.
- clocks: pointer to the reference clock

The DT node must also contains sub-nodes for each XOR channel that the
XOR engine has. Those sub-nodes have the following required
properties:
- interrupts: interrupt of the XOR channel

The sub-nodes used to contain one or several of the following
properties, but they are now deprecated:
- dmacap,memcpy to indicate that the XOR channel is capable of memcpy operations
- dmacap,memset to indicate that the XOR channel is capable of memset operations
- dmacap,xor to indicate that the XOR channel is capable of xor operations
- dmacap,interrupt to indicate that the XOR channel is capable of
  generating interrupts

Example:

xor@d0060900 {
	compatible = "marvell,orion-xor";
	reg = <0xd0060900 0x100
	       0xd0060b00 0x100>;
	clocks = <&coreclk 0>;
	status = "okay";

	xor00 {
	      interrupts = <51>;
	};
	xor01 {
	      interrupts = <52>;
	};
};