tools/hotplug: Write physical-device-path in addition to physical-device

Change block-common.sh on Linux to write physical-device-path with the
path of the device node, in addition to physical-device with its
major:minor numbers.

Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Tested-by: George Dunlap <george.dunlap@citrix.com>

tools/hotplug/Linux/block-common.sh

@@ -67,7 +67,8 @@ write_dev() {
   fi
  
   xenstore_write "$XENBUS_PATH/physical-device" "$mm"
-
+  xenstore_write "$XENBUS_PATH/physical-device-path" "$1"
+  
   success
 }