Let adbd set service.adb.tcp.port.

Commit 67c36884 changed the label of service.adb.tcp.port to allow
vendor init to set it, but accidentally prevented adbd from setting it,
which broke `adb tcpip`.

Bug: http://b/171280882
Test: `adb tcpip`
Change-Id: I154e2f43a4d3b72b27508ce02d66298673939738
4 files changed