[Thread] move ot-daemon socket to /dev/socket/ot-daemon

On Android, unix sockets are located in /dev/socket/ and managed by
init. This commit follows the convention for ot-daemon

Bug: 320451788
Test: verified that ot-daemon can create socket
/dev/socket/ot-daemon/thread-wpan.sock

Change-Id: I6b0fe45602bb54d6d482f5be46ddb5402bea477b
diff --git a/private/file_contexts b/private/file_contexts
index 7fbc580..e58b433 100644
--- a/private/file_contexts
+++ b/private/file_contexts
@@ -167,6 +167,7 @@
 /dev/socket/mdns	u:object_r:mdns_socket:s0
 /dev/socket/mdnsd	u:object_r:mdnsd_socket:s0
 /dev/socket/mtpd	u:object_r:mtpd_socket:s0
+/dev/socket/ot-daemon(/.*)?  u:object_r:ot_daemon_socket:s0
 /dev/socket/pdx/system/buffer_hub	u:object_r:pdx_bufferhub_dir:s0
 /dev/socket/pdx/system/buffer_hub/client	u:object_r:pdx_bufferhub_client_endpoint_socket:s0
 /dev/socket/pdx/system/performance	u:object_r:pdx_performance_dir:s0