Since the tethering functions in ConnectivityService is delegated
to TetheringManager instance and get caches informataion in
TetheringManager without checking ACCESS_NETWORK_STATE permission.
If application use reflection call getTetherXXX functions in
ConnectivityService, it can get tethering status with no additional
execution privileges needed.
Bug: 162952629
Test: manual
Ignore-AOSP-First: security fix
Change-Id: I5b897f216db19fead6ba6ac07915aa0f6ff5bf42
28160b3141