Fix defects detected by static analysis

Fix defects detected by static analysis
 - mediator/submediator sample app.
 - enrolleeSecurity class memory issue.

Change-Id: Ia224aec14001f66085788eced8a4bb059c8e1715
Signed-off-by: Parkhi <h_w.park@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/15673
Reviewed-by: Jihun Ha <jihun.ha@samsung.com>
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Uze Choi <uzchoi@samsung.com>
(cherry picked from commit 9eb66a6863398d7be7f49a890d7b5e2829a97ddc)
Reviewed-on: https://gerrit.iotivity.org/gerrit/15841
Reviewed-by: Kevin Kane <kkane@microsoft.com>