PPC/s390: skip wasm-dynamic-tiering on unsupported platforms

Change-Id: I818534bc2fedd127689bf82f2cdd3a4f2f8c31e8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2310574Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Milad Farazmand <miladfar@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#68977}

test/mjsunit/mjsunit.status

@@ -1147,6 +1147,7 @@
   'wasm/liftoff': [SKIP],
   'wasm/tier-up-testing-flag': [SKIP],
   'wasm/tier-down-to-liftoff': [SKIP],
+  'wasm/wasm-dynamic-tiering': [SKIP],
 }], # arch not in (x64, ia32, arm64, arm)
 
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