The elfloader is going to start using devices based on the device tree.
Add an output method for hardware_gen.py that generates header files
that the elfloader can use. Currently they contain an array of
"devices", where each device has a compatiblity string and a series of
regions (represented simply as the physical address of the region).
For now, the elfloader only uses the serial device specified by the
stdout-path property in the DTB.
7eb4147e43