[roll] Roll fuchsia [kernel] Update documentation on PortObserver

This removes references to the old StateObserver names and return value
scheme and adds more verbiage about the lists and locks PortObserver uses.

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/984975
Original-Revision: bde2309d9108e4d5e913d2e85196e6ae1c05c7ac
GitOrigin-RevId: c3442bff8881ac8fc4f726b531d056ad214d1ac0
Change-Id: Ieb121916269fa924588fff1d8fdb1eec128c1f3a
diff --git a/stem b/stem
index d5fccac..6df815f 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="1894865b6429872afaf91debfe64ce657bf3e15b"/>
+             revision="bde2309d9108e4d5e913d2e85196e6ae1c05c7ac"/>
   </projects>
   <hooks>
     <hook name="install-environment"