tests: Add spaces around '=' in a string comparision in TEST primitive

BUG: 764966
Change-Id: I2da197bdddb4a4d098ebb044410e21ced4dbd806
Signed-off-by: Kaushal M <kaushal@redhat.com>
Reviewed-on: http://review.gluster.org/4618
Reviewed-by: Jeff Darcy <jdarcy@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>