- Implement "fdt mres" sub-command that prints reserved memory regions

- Implement "fdt mres" sub-command that prints reserved memory regions
- Add "fdt addr" subcommand that lets you specify preloaded blob address
- Do not pre-initialize blob for "fdt addr"
- Do not try to load dtb every time fdt subcommand is issued,
    do it only once
- Change the way DTB is passed to kernel. With introduction of "fdt addr"
    actual blob address can be not virtual but physical or reside in
    area higher then 64Mb. ubldr should create copy of it in kernel area
    and pass pointer to this newly allocated buffer which is guaranteed to work
    in kernel after switching on MMU.
- Convert memreserv FDT info to "memreserv" property of root node
    FDT uses /memreserve/ data to notify OS about reserved memory areas.
    Technically it's not real property, it's just data blob, sequence
    of <start, size> pairs where both start and size are 64-bit integers.
    It doesn't fit nicely with OF API we use in kernel, so in order to unify
    thing ubldr converts this data to "memreserve" property using the same
    format for addresses and sizes as /memory node.