gluster: correct GLUSTER_RPM_PACKAGES

The patch makes correct GLUSTER_RPM_PACKAGES
structure for list comprehension (caps.py:454)

Change-Id: Id4c549b7d36d9c44badb0c1edee7c105f1677a00
Signed-off-by: Stanislav Mikhalevich <msio57@gmail.com>
Reviewed-on: http://gerrit.ovirt.org/26379
Reviewed-by: Bala.FA <barumuga@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>