Fixed mark-profile-owner-on-organization-owned-device for non-profile users

It was throwing a NPE as such users are "orphan".

Test: adb shell dpm mark-profile-owner-on-organization-owned-device com.afwsamples.testdpc/.DeviceAdminReceiver
Fixes: 182189140
Change-Id: Ib02d767a23c53c1c2886728c2f338628149f7868