[Qemu-ppc] New u-boot.git mirror on git.qemu-project.org for e500 target

[Stefan Hajnoczi]

Alex asked me to set up a u-boot.git mirror since the e500 ppc target
is now capable of booting u-boot.  This is a nice step since it allows
the target to boot payloads in the same way as real hardware (useful
for booting non-Linux guest operating systems, for example).

The mirror is available here:
git clone git://git.qemu-project.org/u-boot.git

Stefan