[IOT-1605][tizen]Fix obs ocserver.cpp deregistration coredump issue

[IOT-1605][tizen]Fix obs ocserver.cpp deregistration coredump issue

Fix ocserver.cpp obs deregistration coredump issue in tizen.

Change-Id: Iba3f1288482cd20aac585eec599b45764499b09d
Signed-off-by: bg.chun <bg.chun@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/14825
Reviewed-by: Hyuna Jo <hyuna0213.jo@samsung.com>
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Jaewook Jung <jw0213.jung@samsung.com>
Reviewed-by: Jaehong Jo <jaehong.jo@samsung.com>
Reviewed-by: Phil Coval <philippe.coval@osg.samsung.com>
Reviewed-by: Uze Choi <uzchoi@samsung.com>
Reviewed-by: Ziran Sun <ziran.sun@samsung.com>