Add sub-commands to fdt

fdt header                          - Display header info
fdt bootcpu <id>                    - Set boot cpuid
fdt memory <addr> <size>            - Add/Update memory node
fdt rsvmem print                    - Show current mem reserves
fdt rsvmem add <addr> <size>        - Add a mem reserve
fdt rsvmem delete <index>           - Delete a mem reserves

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>