Disable Frontier AMD bench: IBM case hits zero-size GPU transfer bug

The IBM benchmark case crashes with the AMD OpenMP offloading compiler
due to a zero-size host-to-device memory copy that the HSA runtime
rejects (HSA_STATUS_ERROR_INVALID_ARGUMENT). This works fine with CCE.
Disable the AMD bench entry until the underlying issue is fixed.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: sbryngelson

.github/workflows/bench.yml

@@ -74,14 +74,15 @@ jobs:
             device: gpu
             interface: omp
             build_script: "bash .github/workflows/frontier/build.sh gpu omp bench"
-          - cluster: frontier_amd
-            name: Oak Ridge | Frontier (AMD)
-            group: phoenix
-            labels: frontier
-            flag: famd
-            device: gpu
-            interface: omp
-            build_script: "bash .github/workflows/frontier_amd/build.sh gpu omp bench"
+          # frontier_amd bench disabled: IBM case hits zero-size GPU transfer bug with AMD OpenMP offloading
+          # - cluster: frontier_amd
+          #   name: Oak Ridge | Frontier (AMD)
+          #   group: phoenix
+          #   labels: frontier
+          #   flag: famd
+          #   device: gpu
+          #   interface: omp
+          #   build_script: "bash .github/workflows/frontier_amd/build.sh gpu omp bench"
     runs-on:
       group: ${{ matrix.group }}
       labels: ${{ matrix.labels }}