Apply correct SELinux labels to PDX endpoint and channel sockets.

Bug: 37646189
Test: Compiled for sailfish-eng
      Device booted, normal 2D UI works as before
      Was able to run Daydream app and CubeSea (before O1 VR rendering
      path was disabled by recent change in HW composer).

Change-Id: I1f7040324992d3c784f072ea6b64a65fa7ed0589
diff --git a/services/surfaceflinger/surfaceflinger.rc b/services/surfaceflinger/surfaceflinger.rc
index ff6be81..aea602b 100644
--- a/services/surfaceflinger/surfaceflinger.rc
+++ b/services/surfaceflinger/surfaceflinger.rc
@@ -4,6 +4,6 @@
     group graphics drmrpc readproc
     onrestart restart zygote
     writepid /dev/stune/foreground/tasks
-    socket pdx/system/vr/display/client stream 0666 system graphics
-    socket pdx/system/vr/display/manager stream 0666 system graphics
-    socket pdx/system/vr/display/vsync stream 0666 system graphics
+    socket pdx/system/vr/display/client     stream 0666 system graphics u:object_r:pdx_display_client_endpoint_socket:s0
+    socket pdx/system/vr/display/manager    stream 0666 system graphics u:object_r:pdx_display_manager_endpoint_socket:s0
+    socket pdx/system/vr/display/vsync      stream 0666 system graphics u:object_r:pdx_display_vsync_endpoint_socket:s0