Fix warning codes

Fix warning codes

2 warnings are fixed.
1. warning implicit declaration of function
1. warning ignoring return value of 'scanf'

Change-Id: Id7e5caa3902b9a5b4be04b383b4ef54a2b8a68df
Signed-off-by: ch79.cho <ch79.cho@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/12043
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Uze Choi <uzchoi@samsung.com>
(cherry picked from commit cbe6796c41a31510e1d89d22a988a6f3c2a00841)
Reviewed-on: https://gerrit.iotivity.org/gerrit/12461