[roll] Roll fuchsia [kernel][sched] Fix one character bug from GTL breakup

Fix a one character bug introduced by the GTL breakup CL in:

https://fxrev.dev/926125/39/zircon/kernel/kernel/scheduler.cc#1132

Fix the expression to refer to the scale up factor of queue b instead of
queue a. Found while working on the bug referenced below.

Original-Bug: b/322206755
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1153825
Original-Revision: 183f6d93cf27ac2948ad05ba2a6d993ffd961f1b
GitOrigin-RevId: dcfb993007049331cde687d2ca4c6c47cd1ddb9b
Change-Id: I74380db7636df5eca2750f6bcde5d7b114b11e56
diff --git a/stem b/stem
index fae883c..4b8cf3b 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="3a34d43b08195ae77db2be6e52ca72f8d6068595"/>
+             revision="183f6d93cf27ac2948ad05ba2a6d993ffd961f1b"/>
   </projects>
   <hooks>
     <hook name="install-environment"