Remove the unnecessary pv_list assign during LVM object init
Remove the unnecessary pv_list assign during LVM object init

The pv_list of LVM object actually wanted to be a list of dict of
physical volumes' info, but in the routine of creating a new vg,
we assign a list of physical volumes' name to it, which is unnecessary,
and also confuse people.

Change-Id: I3e19c574aa76594898307682c4898d5459c2af76

openstack/cinder,mahak/cinder,phenoxim/cinder,openstack/cinder,j-griffith/cinder,j-griffith/cinder,mahak/cinder,Datera/cinder,phenoxim/cinder,Datera/cinder