VMware: Fixed upload-to-image for available volume

Cinder generally does not allow upload-to-image operation on a volume
that is 'in-use'. This can however be over-ridden using the '--force True'
flag. The VMware driver cannot support upload-to-image when the volume is
in-use. This is a restriction for the VMware driver alone. When the user forces
an upload on a volume that is 'in-use' the Cinder api layer sets the volume
status to 'uploading' and calls into the driver code to upload. In this
scenario the VMware driver needs to fail the operation.

The current driver code here does this check wrongly by looking for volume
status of 'in-use'. Fixing this check to identify an in-use volume correctly.

Fixes bug: 1237338

Change-Id: If54edfdc242a7a1bff442b6bb4c5a9865eede1dc
Merge "VMware: Fixed upload-to-image for available volume"