* File system firmware loader

Required properties:
--------------------

- compatible: should contain "u-boot,fs-loader"
- phandlepart: which block storage device and partition the image loading from,
	       this property is required for mmc, usb and sata. This is unsigned
	       32-bit array. For example phandlepart=<&mmc_0 1>, meaning use
	       that MMC0 node pointer, partition 1.
- mdtpart: which partition of ubi the image loading from, this property is
	   required for ubi and mounting.
- ubivol: which volume of ubi the image loading from, this property is required
	  for ubi and mounting.

Example of storage device and partition search set for mmc, usb, sata and
ubi in device tree source as shown in below:

	Example of storage type and device partition search set for mmc, usb,
	sata and ubi as shown in below:
	Example for mmc:
	fs_loader0: fs-loader@0 {
		u-boot,dm-pre-reloc;
		compatible = "u-boot,fs-loader";
		phandlepart = <&mmc_0 1>;
	};

	Example for usb:
	fs_loader1: fs-loader@1 {
		u-boot,dm-pre-reloc;
		compatible = "u-boot,fs-loader";
		phandlepart = <&usb0 1>;
	};

	Example for sata:
	fs_loader2: fs-loader@2 {
		u-boot,dm-pre-reloc;
		compatible = "u-boot,fs-loader";
		phandlepart = <&sata0 1>;
	};

	Example for ubi:
	fs_loader3: fs-loader@3 {
		u-boot,dm-pre-reloc;
		compatible = "u-boot,fs-loader";
		mtdpart = "UBI",
		ubivol = "ubi0";
	};
