[roll] Roll fuchsia Revert "[display][banjo] Delete OnDisplaysChanged()."

This reverts commit e8875c3055bf2ccffbd8a5c71e598964b3f5cd99.

Reason for revert: possibly broke NUC11 builders

Original change's description:
> [display][banjo] Delete OnDisplaysChanged().
>
> This event is not used by display engine drivers anymore and it's
> safe to delete it.
>
> Test: fx build
> Original-Fixed: 339311596
> Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1045592

No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1046394
Original-Revision: 9af7129a9079db17f46595c71f4292fdec93bbf6
GitOrigin-RevId: 48e0f07c4c90939476b86b5b7581dbfb37c7ce3b
Change-Id: I983b3e99fa9f904a47c80748a46c7b4664a0db78
diff --git a/stem b/stem
index 2757706..1b2eac8 100644
--- a/stem
+++ b/stem
@@ -11,7 +11,7 @@
              githooks="integration/git-hooks"
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="dd7557d95161c1e30014d441ce2df679eb1814f0"/>
+             revision="9af7129a9079db17f46595c71f4292fdec93bbf6"/>
   </projects>
   <hooks>
     <hook name="install-environment"