Return provider_id in SolidFire model update

Return provider_id in SolidFire model update

The provider_id field was added in
commit: 9f34d34d0ab92400223e3cc87285d0d4fbdf21f9

This patch adds provider_id to the returned model
update and uses it to provide the internal SolidFire
volume ID mapping.

Next step will be to rewrite the awkward list search
of volume names to find the corresponding volume on
the SolidFire backend.

Change-Id: Ia44d46362bb1b688c4ac266afecca9ce66dcef25