Add sepolicy SF native boot namespace.

Following go/android-native-flag-api-manual.

Bug: 190769260
Test: make.
Change-Id: I84fe7e9d046fbbe737f09043589b19e71981f521
diff --git a/private/surfaceflinger.te b/private/surfaceflinger.te
index 8203724..f99ce96 100644
--- a/private/surfaceflinger.te
+++ b/private/surfaceflinger.te
@@ -61,6 +61,7 @@
 
 # Get properties.
 get_prop(surfaceflinger, qemu_sf_lcd_density_prop)
+get_prop(network_stack, device_config_surface_flinger_native_boot_prop)
 
 # Use open files supplied by an app.
 allow surfaceflinger appdomain:fd use;