Now that we have a mirror of this repo on git.qemu.org change the
submodule to use that and update it to latest commit which fixes a
dangling symlink and removes two big binaries that are not needed.

Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>