This adds a userspace linux utility that writes the u-boot image to an mtd
partition on the docg4 nand flash.

A special utility is required to do this because u-boot is partially loaded by
an initial program loader (IPL) that is permanently programmed to the boot
region of the flash.  This IPL expects the image to be written in a unique
format. The characteristics of this format can be summarized as follows:
  - Flash blocks to be loaded must have a magic number in the oob bytes of the
    first page of the block.
  - Each page must be written redundantly in the subsequent page.
  - The integrated flash controller's "reliable mode" is used, requiring that
    alternate 2k regions (4 pages) are skipped when writing.
For these reasons, a u-boot image can not be written using nandwrite from
mtd-utils.

Signed-off-by: Mike Dunn <mikedunn@newsguy.com>