AOP (Always-On-Processor) DDR Related Messaging

The AOP DDR messaging driver is used to send messages to the AOP,
using the mailbox interface, to lower the DDR frequency during reboot.

Required properties

- compatible : "qcom,aop-ddr-msgs"
- mbox : QMP mailbox phandle and channel identifier

Optional properties:
-mbox-name: name of the mailbox

Example:
	qcom,aop-ddr-msgs {
		compatible = "qcom,aop-ddr-msgs";
		mboxes = <&qmp_aop 0>;
	};