[IOT-1482] fix getPlatformInfo and getDeviceInfo of C++-SDK sample app.

[IOT-1482] fix getPlatformInfo and getDeviceInfo of C++-SDK sample app.

cause patch : https://gerrit.iotivity.org/gerrit/#/c/12909/

Change-Id: If50cba713a67239619047ccb012678f73fb42682
Signed-off-by: jihwan.seo <jihwan.seo@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/13677
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Jaehong Jo <jaehong.jo@samsung.com>
Reviewed-by: Jaewook Jung <jw0213.jung@samsung.com>
Reviewed-by: Ziran Sun <ziran.sun@samsung.com>