Support unicast discovery of secure resource for BLE transport in easy setup

Support unicast discovery of secure resource for BLE transport in easy setup

In a patch, https://gerrit.iotivity.org/gerrit/#/c/15183/, an api to discover
a secure resource in unicast is being developed. So if an OCResource object
given for easy setup is BLE transport, this patch will make a secure resource
discovery happen in unicast due to its better efficiency.

Change-Id: I65bacf090b6ef5cebdb101a705a58ebdb6d8b645
Signed-off-by: Jihun Ha <jihun.ha@samsung.com>
Signed-off-by: Parkhi <h_w.park@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/15205
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Uze Choi <uzchoi@samsung.com>
(cherry picked from commit 1b17f573c2ae4accb5888d69b6038cc252e43554)
Reviewed-on: https://gerrit.iotivity.org/gerrit/15319