vdsm: create /etc/modules-load.d/vdsm.conf

systemd-modules-load.service(8) reads from
/etc/modules-load.d/<program>.conf the kernel modules
required to be loaded during the boot.

This patch creates /etc/modules-load.d/vdsm.conf
which will hold all kernel modules required by VDSM.

Change-Id: I026ff658482ccefbdcc384785cdec10cf934b7d9
Signed-off-by: Douglas Schilling Landgraf <dougsland@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/11718
Reviewed-by: Dan Kenigsberg <danken@redhat.com>