gluster: Modify calls to fnSplitterUuid

Patch http://gerrit.ovirt.org/9825 changed the definition of the SP
fnSplitterUuid in such a way that the older calls to this SP, that
looked like:

select ID from fnSplitterUuid(v_ids)

no longer work, and now need to be changed to something like:

select * from fnSplitterUuid(v_ids)

While this change was done in most of the *_sp.sql scripts, it was
missed out in gluster_volumes_sp.sql

Changing it now in gluster_volumes_sp.sql

Change-Id: I64e0ea2dd7bfb03494aa0346d2aa24b226a99452
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=901531
Signed-off-by: Shireesh Anjal <sanjal@redhat.com>