The make rules for the systemd socket unit files are all essentially
identical and can be collapsed into a single generic rule. The service
unit file rule can be simplified too.
Reviewed-by: NChristophe de Dinechin <dinechin@redhat.com>
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>