*Device-Tree bindings for ST SW reset functionality

Required properties:
- compatible: should be "stih407-restart".
- st,syscfg: should be a phandle of the syscfg node.

Example node:
	restart {
		compatible = "st,stih407-restart";
		st,syscfg = <&syscfg_sbc_reg>;
		status = "okay";
	};
