Fixed copy image to volume and clone volume.

This patch fixed the following issues in EMC driver found during G3 testing:
1. VNX array has two storage processors and it is doing load balancing when
attaching a LUN to a host. The storage processor used to attach a LUN to a
host is different from the one discovered by the driver sometimes, causing
Copy Image to Volume to fail.
2. The clone relationship is removed after a volume is successfully
cloned. However, this happens too soon sometimes before the cloned volume
is fully synced with the source volume.  The fix is to wait until it is
fully synced.

Change-Id: I5b8fab263723c47faf30b950a611c5bde7f29092
Fixes: bug #1135221