tools/hotplug: fix race during xen.conf creation

tools/hotplug: fix race during xen.conf creation

A make -j8 will call the xen.conf rule twice. The move-if-changed
macro may fail if the tmp file was already removed by the other make
process. Fix this by let the all target depend on install.
Also remove the generated file with make clean.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
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>
[ ijc -- fixed s/of/if/ typo in commit message ]