UBUNTU: [Packaging] disable hv-kvp-daemon if needed

UBUNTU: [Packaging] disable hv-kvp-daemon if needed

BugLink: https://bugs.launchpad.net/bugs/2024900
The daemon reads from this vmbus, if it is not present, it will just
exit with an error. Adding this line to the service file will prevent
systemd from trying to start the daemon if the device is not present.

Signed-off-by: Gauthier Jolly <gauthier.jolly@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Andrei Gherzan <andrei.gherzan@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Roxana Nicolescu <roxana.nicolescu@canonical.com>