VMware: Added check for datastore state before selection

The driver only checked for the datastore type. The datastore could
be in an inaccessible state. In such cases creating an instance to
such datastore will fail. The fix to filter out inaccessible data-
stores.

The datastores have a property called accessible. The fix is to use
this property to filter out inaccessible datastores.

fix bug #1194078

Change-Id: I372fc3adc0e89c48d86f1f70164263ed35184c5d
Merge "VMware: Added check for datastore state before selection"