Rename surfaceflinger properties' contexts

Cleaning up exported*_system_prop and moving surfaceflinger properties
to new property contexts.

Bug: 152468529
Bug: 154885206
Test: boot cf_x86 and crosshatch
Change-Id: I7f8a684e9cbabce2f55a5292d7b2283ac0716cd9
diff --git a/private/property.te b/private/property.te
index 84651ef..d479502 100644
--- a/private/property.te
+++ b/private/property.te
@@ -331,3 +331,11 @@
 } {
   userspace_reboot_test_prop
 }:property_service set;
+
+neverallow {
+  -init
+  -system_server
+  -vendor_init
+} {
+  surfaceflinger_color_prop
+}:property_service set;