hotplug/Linux: remove hotplug support, rely on udev instead

hotplug/Linux: remove hotplug support, rely on udev instead

Hotplug has been replaced by udev since several years. Remove the
hotplug related files and install udev unconditionally.

This makes it possible to remove udev from rpm BuildRequires which
reduces the buildtime dependency chain. For openSuSE:Factory it was
done just now:
http://lists.opensuse.org/opensuse-buildservice/2012-10/msg00085.html

The patch by itself will have no practical impact unless someone
attempts to build and run a Xen dom0 on a really old base system. e.g.
circa SLES9/2007 or earlier

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Campbell <ian.campbell@citrix.com>