Storwize/SVC driver fix for multibackend scenario.

In order for the Filter scheduler to be used to it's full advantage
Cinder drivers need to move away from using FLAGS directly and switch
to appending their specific options to self.configuration.

Fixes bug: 1135391

Change-Id: I8d07346c03d1cf2479738f7161ee0a0cb9f518a0
Merge "Storwize/SVC driver fix for multibackend scenario."