Remove dead qemu code from toplevel Makefile

Remove dead qemu code from toplevel Makefile

After commit b0f69ec5c71de1248d915c193b57c43e786857dd ("tools: Make
qemu-xen-traditional build optional.") the existing make targets are
wrapped in ifeq ($(CONF),y), but CONF is never set because
config/Tools.mk is not included.

Drop the dead code. The same effect can be achieved by calling the make
commands directly, after calling configure.

A better approach would be a simple, single 'make $something' which
should be a wrapper around a targets in tools/Makefile that clones,
updates and cleans the subprojects. That has to be worked out in a
different patch.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>