SR-IOV interfaces are currently only configured on charm
installation and not after seubsequent reboots.
The VFs need to be configured before the Neutron SR-IOV
agent is started. Charms should also really not be involved
in boot time system configuration. Due to these factors
this commit adds a init script and corrensponding systemd
unit file and upstart job to handle the boot-time configuration.
Keep configure_sriov function for runtime configuration. Add
warning about runtime configuration disrupting network service.
Add restart of Neutron SR-IOV agent after runtime configuration.
Cap value of sriov-numvfs at each interfaces sriov_totalvfs value.
Change-Id: I7bde7217bf027db09ded35a262c214ccb11d6d86
Closes-Bug: #1697572
4ffbc2fe25