Config: Switch to unified qemu trees.

Config: Switch to unified qemu trees.

Upstream qemu is now in qemu-xen.git and the trad fork is in
qemu-xen-traditional.git.

QEMU_UPSTREAM_REVISION is currently a tag and
QEMU_TRADITIONAL_REVISION is a specific revision, so no changes are
required to those.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Conflicts:
	Config.mk
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
(cherry picked from commit 78833c04250416f1870c458309d3ac0e5cf915fd)

Conflicts:
	Config.mk
(cherry picked from commit 0cabed0a0b322fbef30f3519465538df4ab1d9f2)

Conflicts:
	Config.mk