Specify the correct Samba share path

When configuring a new Samba share, the generic driver doesn't specify
the correct share path. It specifies "path = /shares" instead of "path =
/shares/share-GUID". As a result, a host with access to one share can
access any other shares deployed by the tenant.

Change-Id: I8ec94c522f65cd66f5e53841ac73d078973c6b85
Closes-Bug: #1370223
Merge "Specify the correct Samba share path"