[llvm] [AMDGPU][AsmParser]: Use dummy operand for parsing buffer_ SWZ operand. (PR #165305)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-ppc64le-linux-test-suite` running on `ppc64le-clang-test-suite` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/95/builds/18975

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test-build-unified-tree-check-all) failure: 1200 seconds without output running [b'ninja', b'check-all'], attempting to kill
...
0.800 [2/3/1] Building CXX object compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_dynamic_version_script_dummy.powerpc64le.dir/dummy.cpp.o
0.915 [1/3/2] Building CXX object compiler-rt/lib/asan/CMakeFiles/RTAsan_dynamic_version_script_dummy.powerpc64le.dir/dummy.cpp.o
1.765 [0/3/3] Linking CXX shared library /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/lib/clang/22/lib/powerpc64le-unknown-linux-gnu/libclang_rt.ubsan_standalone.so
3.360 [0/2/4] Linking CXX shared library /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/lib/clang/22/lib/powerpc64le-unknown-linux-gnu/libclang_rt.asan.so
5.755 [0/1/5] Generating /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/compile_commands.json
57.308 [3/78/12] cd /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/runtimes/runtimes-bins && /home/buildbots/llvm-external-buildbots/cmake-3.31.2/bin/cmake --build /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/runtimes/runtimes-bins/ --target runtimes-test-depends --config Release
ninja: no work to do.
57.821 [2/78/13] No install step for 'runtimes'
58.231 [1/78/15] Completed 'runtimes'
440.822 [1/77/16] Preparing lit tests
command timed out: 1200 seconds without output running [b'ninja', b'check-all'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=1641.482621

```

</details>

https://github.com/llvm/llvm-project/pull/165305