[roll] Roll fuchsia [msd_cpp_to_c] Return null on device failure

If we fail to create a device return a nullptr instead of an msd::Device
that holds a nullptr.

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1253505
Original-Revision: 20b844f482cf9982d58963b7cdd368edc072bba3
GitOrigin-RevId: f218edd8cd2e351a062f6e6813c99747a99a3e13
Change-Id: I0fd0155dd128067e21ee93afd34cc059ac7c3e00
diff --git a/stem b/stem
index 135506c..fc5b0e5 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="e05da63dc6e15ab21a8d6ebef9717258ea244fac"
+             revision="20b844f482cf9982d58963b7cdd368edc072bba3"
              />
   </projects>
   <hooks>