[roll] Roll fuchsia [kernel][vm] Don't own range in SupplyPages

With share counts it is no longer necessary to take owenership of the
entire range in SupplyPagesLocked, it is sufficient to decrement the
share count in the case that a page is supplied into a slot would have
seen a page in the parent chain.

Original-Bug: 434536251
Run-All-Tests: True
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1420634
Original-Revision: ca81fb6aeddf7336d667866b934ffefbe8f556d5
GitOrigin-RevId: e9366d8810852289cb6698eabab62e9500358568
Change-Id: I55c370799d1bf43addabbe8a6e8554cecc699aaa
diff --git a/stem b/stem
index 53b10f9..d5c42b5 100644
--- a/stem
+++ b/stem
@@ -7,7 +7,7 @@
             manifest="manifests/platform"
             root=""
             remote="https://fuchsia.googlesource.com/fuchsia"
-            revision="b864deeb6b4ec04c827acce53fb31bffede3d6cc"/>
+            revision="ca81fb6aeddf7336d667866b934ffefbe8f556d5"/>
   </imports>
   <projects>
     <project name="cobalt"