Remove unnecessary OC API in Provisioning Manager

Remove unnecessary OC API in Provisioning Manager
- OCDeleteProvisionResults() is not required any more
  because OCProvisionResult_t is freed after user callback is hitted.

Change-Id: I6daa2eeb869121944b3839257129496cb5fb9321
Signed-off-by: Woochul Shim <woochul.shim@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/2422
Reviewed-by: Randeep Singh <randeep.s@samsung.com>
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Sakthivel Samidurai <sakthivel.samidurai@intel.com>
Reviewed-by: Sachin Agrawal <sachin.agrawal@intel.com>