brillo: add support for adb over TCP.
Brillo devices may sometimes want to connect to adb via TCP rather than
USB, e.g. for boards that don't have USB or need to use the USB port
for a different purpose.
This CL makes this easy by providing a make function to specify the adb
port, and by automatically opening the correct firewall holes for adb.
This also reverts http://r.android.com/185850 which was a temporary fix
to always open port 5555.
Bug: http://b/26082438
Test: Add $(call enable_adb_over_tcp, 5555) to BoardConfig.mk
`adb connect <ip>:5555` successfully connects device.
Test: Call `adb tcpip 5555` with standard BoardConfig.mk
`adb connect <ip>:5555` successfully connects device.
Change-Id: Ie3ac630416013fa610ef64e8c82faa29c73c3c10
7 files changed
