Fixes dettach volumes in Windows cinder plugin

The patch fixes issues when desassigning target to initiators
in the terminate_connection method. The method now takes
the right parameter coming from provider location.

Change-Id: I2ea1ac7f46e3a24a6493af8eba46a113126e1117
Fixes: bug #1153968
Merge "Fixes dettach volumes in Windows cinder plugin"