[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-aarch64-quick` running on `linaro-clang-aarch64-quick` while building `llvm` at step 5 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/65/builds/24604

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

```
Step 5 (ninja check 1) failure: stage 1 checked (failure)
******************** TEST 'Clangd Unit Tests :: ./ClangdTests/70/335' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/home/tcwg-buildbot/worker/clang-aarch64-quick/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests-Clangd Unit Tests-3417469-70-335.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=335 GTEST_SHARD_INDEX=70 /home/tcwg-buildbot/worker/clang-aarch64-quick/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests
--

Script:
--
/home/tcwg-buildbot/worker/clang-aarch64-quick/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests --gtest_filter=LSPTest.Diagnostics
--
<<< initialize: {}
<-- initialize(0)
--> reply:initialize(0) 119 ms
>>> reply: {
  "capabilities": {
    "astProvider": true,
    "callHierarchyProvider": true,
    "clangdInlayHintsProvider": true,
    "codeActionProvider": true,
    "compilationDatabase": {
      "automaticReload": true
    },
    "completionProvider": {
      "resolveProvider": false,
      "triggerCharacters": [
        ".",
        "<",
        ">",
        ":",
        "\"",
        "/",
        "*"
      ]
    },
    "declarationProvider": true,
    "definitionProvider": true,
    "documentFormattingProvider": true,
    "documentHighlightProvider": true,
    "documentLinkProvider": {
      "resolveProvider": false
    },
    "documentOnTypeFormattingProvider": {
      "firstTriggerCharacter": "\n",
      "moreTriggerCharacter": []
    },
    "documentRangeFormattingProvider": {
      "rangesSupport": true
    },
    "documentSymbolProvider": true,
    "executeCommandProvider": {
...

```

</details>

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