Need to update the changed flavors during syncing the flavors

Now the PowerVC driver will not reflect the change of the flaovr
in the PowerVC side.

Add the new logic in the sync flavor program. Update the flavor
extra_specs during syncing the existing flavors.

Change-Id: I470904703274f004f4dfa1d7dc375339d8d46921
Closes-Bug: 1340036