ovs-ctl: fix system-id.conf owner

ovs-ctl: fix system-id.conf owner

As far as RPMs are concerned, system-id.conf file is declared as being
owned by openvswitch.
At the first ovs startup, ovs-ctl creates this file if none exists without
ensuring this.

We end up with an inconsistency:
$ rpm -V openvswitch
.....UG..  c /etc/openvswitch/system-id.conf

Fix this when ovs-ctl is the one who creates the file.

Note: this issue ends up being hidden after a RPM upgrade, since the
openvswitch user is enforced on the whole /etc/openvswitch directory as a
%post operation.

Acked-by: Timothy Redaelli <tredaelli@redhat.com>
Acked-by: Flavio Leitner <fbl@sysclose.org>
Signed-off-by: David Marchand <david.marchand@redhat.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>