Fixed compiler warnings

Fixed compiler warnings

Fixed compiler warnings in security layer due to recently enable compiler flags.

Change-Id: Id88c7385bb493074fab40513745702f6b452590d
Signed-off-by: Shilpa Sodani <shilpa.a.sodani@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/2164
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Sachin Agrawal <sachin.agrawal@intel.com>