Fix VTS errors of the network scan API

Since the new network scan API is only supported by some devices, we
should add the REQUEST_NOT_SUPPORTED to the possible returned errors.

Cherry-picked cleanly from:
https://googleplex-android-review.git.corp.google.com/#/c/2596051/

Test: Telephony sanity tests, run vts -m VtsHalRadioV1_1Target
Bug: 63914600
Merged-in: I965ee6422aaa5e02bf67466f5288b808183f1738
Change-Id: I965ee6422aaa5e02bf67466f5288b808183f1738
(cherry picked from commit 03c6b592)