Fix 'no actual-pathname' NetApp API error

Fix 'no actual-pathname' NetApp API error

Cinder volume logs sometimes show this error

      NetApp API failed. Reason - 13114:
      No actual-pathname for 10.1.0.9:/vol/whatever

with Kilo code and 7-mode DOT system.

The issue is due to our Cinder driver passing the
entire share to the relevant API instead of just
the export path portion of the share.  This only
happens when the NFS image cache is full, and cached
files need to be removed.

Change-Id: I0c40840dac975dd7fd2c62f1f9c0cd3f8c5c1252
Closes-Bug: #1468884