Move the definitions of the fdt functions from a uboot header to a new fdt
header. There is nothing in the fdt spec that ties it to U-Boot.
While here sort and fix the signature of fdt_setup_fdtp.
MFC 273934:
Start to allow platforms other than U-Boot to use the FDT code in loader by
moving U-Boot specific code from libfdt.a to a new libuboot_fdt.a. This
needs to be a new library for linking to work correctly.
Differential Revision: https://reviews.freebsd.org/D1054
Reviewed by: ian, rpaulo (earlier version)
35401942c2