SIPA delegator for Spreadtrum platforms

Required properties:
- compatible: should be one of following:
	"sprd,roc1-sipa-delegate",
	"sprd,orca-sipa-delegate".
- reg: Specify the physical base address of the controller and length
  of memory mapped region.
- sprd,ul-fifo-depth:
	Specify uplink transfer fifo total depth.
- sprd,dl-fifo-depth:
	Specify downlink transfer fifo total depth.

Examples:
	ipa_delegate: sipa-dele@2e000000 {
		compatible = "sprd,roc1-sipa-delegate";
		reg = <0x0 0x2e000000 0 0x00001000>,
		      <0x3 0x8e000000 0 0x00001000>;
		reg-names = "remote-base", "mapped-base";

		sprd,ul-fifo-depth = <1024>;
		sprd,dl-fifo-depth = <1024>;
	};