Support TCP based fastbootd in recovery mode.

The IPv6 link-local address is used to avoid expose device to out of
network segment.

BUG: 152544169
BUG: 155198345
Test: manual test.
Change-Id: I0ce8c12de9976c01e57a6433c7fb50235e907dc5
Merged-In: I0ce8c12de9976c01e57a6433c7fb50235e907dc5
Merged-In: I409aeccd31293bf0ae3be5b1dbafe5a74daaaa9d
diff --git a/private/property_contexts b/private/property_contexts
index a117fcc..1a5471f 100644
--- a/private/property_contexts
+++ b/private/property_contexts
@@ -97,6 +97,9 @@
 sys.lmk.                u:object_r:system_lmk_prop:s0
 sys.trace.              u:object_r:system_trace_prop:s0
 
+# Fastbootd protocol control property
+fastbootd.protocol    u:object_r:fastbootd_protocol_prop:s0 exact enum usb tcp
+
 # Boolean property set by system server upon boot indicating
 # if device is fully owned by organization instead of being
 # a personal device.