Clear the caller identity after the permission is verified

For the method requestNetworkScan(...), the caller identity was cleared
after verifying the permission in aosp/722888, but in a later cl
aosp/836166, this logic was removed which is causing issues.

Bug: 128480460
Test: manual test
Change-Id: I3af80b6b3ae3df31ed0f844535793b5fbe4bbc7e
1 file changed