Fixed memory leak from keep-alive
Fixed memory leak from keep-alive

The keep-alive mechanism was not properly deleting the payload
that was created for keep-alive.

Change-Id: I80736893e472c31f9058c2d2b5c1d3c38a692c04
Signed-off-by: hyuna0213.jo <a3aecee2eabd6f87461b5d05d6fd0eaf35e269ed@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/10223
Reviewed-by: jihwan seo <69598d7552022c520cfdbefd16641727c7ff4ab5@samsung.com>
Tested-by: jenkins-iotivity <09cb29e8a2b473a2c978382eec13ee06fa017bda@opendaylight.org>
Reviewed-by: Jaehong Jo <69db334b3f87f30654728856fde276b43c835fe5@samsung.com>
Reviewed-by: Ashok Babu Channa <72ac47ef856ca3d131a57cba474ebed48591eeff@samsung.com>

rzr/iotivity,iotivity/iotivity,rzr/iotivity,iotivity/iotivity,iotivity/iotivity,iotivity/iotivity,rzr/iotivity,rzr/iotivity,iotivity/iotivity,iotivity/iotivity,rzr/iotivity,rzr/iotivity,iotivity/iotivity,rzr/iotivity,iotivity/iotivity