[roll] Roll fuchsia [kernel][armv7_mmio_timer] Make static member C++23-compatible

New C++23 rules (as presently enforced by Clang/libc++ anyway)
preclude using unique_ptr<IncompleteType> in more places that it
worked before.  A class type is still incomplete while its own
static member variables are being declared.  They can be declared
without instantiating their type, but they cannot be _defined_
and a `static inline` data member declaration is a definition.
So the definition (still `inline`) moves outside the class, to
where that class has become a complete type.

Original-Bug: 459923005
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1430256
Original-Revision: e59457c507de76d7e26a47ae306773fb62af7aee
GitOrigin-RevId: c2f7fbfa3fd48800c92c851ffa3b0e2618b7a17b
Change-Id: I97db43b2eb5072790443d06fdc9a9bd7f603a9fa
diff --git a/stem b/stem
index a374cf6..0746afc 100644
--- a/stem
+++ b/stem
@@ -7,7 +7,7 @@
             manifest="manifests/platform"
             root=""
             remote="https://fuchsia.googlesource.com/fuchsia"
-            revision="94d2017e9929b9d9e3c2073ee377b7886d42ab84"/>
+            revision="e59457c507de76d7e26a47ae306773fb62af7aee"/>
   </imports>
   <projects>
     <project name="cobalt"