[cube][fuchsia] Fix vkcube-on-fb-protected display permissions

This CL is equivalent to I75e51f7b77b5f0f9e65b6afcef6049c199febf44 and
I484fb76112f223e725347cec3a4d7e4dbf86ea19 but tackles
vkcube-on-fb-protected.

Test: fx test vkcube-on-fb-protected on core.nelson
Change-Id: Idf0dfe732b977d97501881b6995bae0a543aaa36
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/Vulkan-Tools/+/858259
Fuchsia-Auto-Submit: Victor Costan <costan@google.com>
Reviewed-by: Craig Stout <cstout@google.com>
Commit-Queue: Auto-Submit <auto-submit@fuchsia-infra.iam.gserviceaccount.com>
diff --git a/cube/fuchsia/meta/vkcube-on-fb-protected.cml b/cube/fuchsia/meta/vkcube-on-fb-protected.cml
index 5b07458..4b571f7 100644
--- a/cube/fuchsia/meta/vkcube-on-fb-protected.cml
+++ b/cube/fuchsia/meta/vkcube-on-fb-protected.cml
@@ -15,7 +15,7 @@
     use: [
         {
             directory: "dev-display-coordinator",
-            rights: [ "rw*" ],
+            rights: [ "r*" ],
             path: "/dev/class/display-coordinator",
         },
     ],