It is quite complicated to run U-Boot on QEMU since we have four
different builds and they must use different versions of qemu and the
UEFI binaries.
Add a script to help. It requires U-Boot itself to be built. Once that
is done you can use this script to build an image for use with qemu and
optionally run it.
Signed-off-by: Simon Glass <sjg@chromium.org>
