Fix to get only single credential entry

Fix to get only single credential entry

Old function(GetCredResourceDataByCredId) return not only the indicated credential entry but also all linked entries.

Change-Id: I0466b4c25a21395f08664a11ecfa6fd51a94b258
Signed-off-by: Joonghwan Lee <jh05.lee@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/13547
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Kevin Kane <kkane@microsoft.com>
Reviewed-by: Randeep Singh <randeep.s@samsung.com>
(cherry picked from commit f849ddefea68e5668900f274976d440931818ef3)
Reviewed-on: https://gerrit.iotivity.org/gerrit/13693
Reviewed-by: Chul Lee <chuls.lee@samsung.com>