fastbootd: Support TCP protocol.

The current fastbootd only supports USB protocol. But some Android TV
devices are built without USB port. The fastbootd cannot be used on
those ATV devices due to it.
This change adds TCP protocol for such devices and fastbootd.protocol
property is added to control which protocol to use.

BUG: 152544169
BUG: 155198345
Test: manual test.
Change-Id: Idc391e677eb6a1880036419ba5f6c4160e8dbcbc
Merged-In: Idc391e677eb6a1880036419ba5f6c4160e8dbcbc
5 files changed