sriov: update port state even if ip link fails

sriov: update port state even if ip link fails

Some SRIOV drivers/devices don't support link state setting,
meaning that 'ip link' fails like this when trying to set state:

 # ip l set dev p2p1 vf 6 state disable
 RTNETLINK answers: Operation not supported

The sriov-nic-agent tries to do that in
SriovNicSwitchAgent.treat_device() and fails because of non-zero
exit status from 'ip link' and, therefore, doesn't reach the code
that updates the actual port status, so port could hang in a BUILD
state even if binding was successful.

This patch fixes problem of nova not being able to successfully bind
or cleanup such a port. It does not fix a case when user manually
updates admin_state_up for a port via API, it's subject to a separate
fix.

Also, replace LOG.exception with LOG.warning for set_device_state()
as the exception would be logged by PciDeviceIPWrapper.set_vf_state()
anyway.

Closes-bug: #1468332
Change-Id: Ifa7c128d369ced60b5986aa0ed92527868f7efab