[IOT-1586] Changed the policy key name for tcp discovery

[IOT-1586] Changed the policy key name for tcp discovery

The name of "x.org.iotivity.tcp" key was changed from
"x.org.iotivity.tcp" to "tcp".

Change-Id: I7bae43f823bdbe744a1cda28b27b9c72d22af996
Signed-off-by: hyuna0213.jo <hyuna0213.jo@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/14607
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Phil Coval <philippe.coval@osg.samsung.com>
Reviewed-by: Jaehong Jo <jaehong.jo@samsung.com>
Reviewed-by: Ziran Sun <ziran.sun@samsung.com>
(cherry picked from commit 37c7550bc5c1c032bd4ed7a5853c98c536914782)
Reviewed-on: https://gerrit.iotivity.org/gerrit/14733
Reviewed-by: Dan Mihai <Daniel.Mihai@microsoft.com>