[IOT-1575] Initialize socket fd after closing session

[IOT-1575] Initialize socket fd after closing session

- add socket fd initialization after closing TCP session in tcpserver

Change-Id: Icb40f0c37ccc17ee9972974cfeae752e3a60048d
Signed-off-by: Hyuna Jo <hyuna0213.jo@samsung.com>
Signed-off-by: Minji Park <minjii.park@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/14499
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: jihwan seo <jihwan.seo@samsung.com>
Reviewed-by: Uze Choi <uzchoi@samsung.com>
Reviewed-by: Ashok Babu Channa <ashok.channa@samsung.com>