Allow tethering find netork stack service

Allow tethering service which is running in the same process as network
stack service "find" network stack service. Original design is passing
network_stack binder to tethering service directly when tethering
service is created. To allow creating tethering service and network
stack service in parallel. Let tethering service query network_stack
binder instead.

Bug: 144320246
Test: boot, flash, build
      OFF/ON hotspot

Change-Id: Ife0c2f4bdb2cfee4b5788d63d1cfc76af0ccc33c
1 file changed