Spreadtrum 7sreset bindings

This IP block in the unisoc SoC that only deals with hardware reboot-force.

Required properties:
- compatible:
  -"sprd,sc2720-7sreset" for SC2720 poweroff
  -"sprd,sc2721-7sreset" for SC2721 poweroff
  -"sprd,sc2730-7sreset" for SC2730 poweroff
  -"sprd,sc2731-7sreset" for SC2731 poweroff

- reg: Specifies the physical address of the 7sreset register.

Example:
hw_reset@1bc0 {
	compatible = "sprd,sc27xx-7sreset", "sprd,sc2730-7sreset";
	reg = <0x1bc0>;
};
