Add the HiBy R1 and X1600 USB boot path, sharing the boot-package reader
with X1000. Load the returning USB stage separately from the flash SPL,
check its DDR result, then upload and run the second-stage bootloader.
Built on macOS; error paths checked with mocked USB transfers.
Change-Id: I501c1ffdb9e3d5f0c76a379ec6d229ec579bf100
rbutil uses several components from the utils folder, and can be
considered part of utils too. Having it in a separate folder is an
arbitrary split that doesn't help anymore these days, so merge them.
This also allows other utils to easily use libtools.make without the
need to navigate to a different folder.
Change-Id: I3fc2f4de19e3e776553efb5dea5f779dfec0dc21
