The Broadcom Secure Processing Unit (SPU) hardware supports symmetric
cryptographic offload for Broadcom SoCs. A SoC may have multiple SPU hardware
blocks.

Required properties:
- compatible: Should be one of the following:
  brcm,spum-crypto - for devices with SPU-M hardware
  brcm,spu2-crypto - for devices with SPU2 hardware
  brcm,spu2-v2-crypto - for devices with enhanced SPU2 hardware features like SHA3
  and Rabin Fingerprint support
  brcm,spum-nsp-crypto - for the Northstar Plus variant of the SPU-M hardware

- reg: Should contain SPU registers location and length.
- mboxes: The mailbox channel to be used to communicate with the SPU.
  Mailbox channels correspond to DMA rings on the device.

Example:
	crypto@612d0000 {
		compatible = "brcm,spum-crypto";
		reg = <0 0x612d0000 0 0x900>;
		mboxes = <&pdc0 0>;
	};