[llvm] [M68k] always use movem for register spills (PR #106715)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clangd-ubuntu-tsan` running on `clangd-ubuntu-clang` while building `llvm` at step 6 "test-build-clangd-clangd-index-server-clangd-in...".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/134/builds/12777

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

```
Step 6 (test-build-clangd-clangd-index-server-clangd-in...) failure: test (failure)
******************** TEST 'Clangd Unit Tests :: ./ClangdTests/16/21' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/vol/worker/clangd-ubuntu-clang/clangd-ubuntu-tsan/build/tools/clang/tools/extra/clangd/unittests/./ClangdTests-Clangd Unit Tests-857188-16-21.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=21 GTEST_SHARD_INDEX=16 /vol/worker/clangd-ubuntu-clang/clangd-ubuntu-tsan/build/tools/clang/tools/extra/clangd/unittests/./ClangdTests
--

WARNING: ThreadSanitizer: unexpected memory mapping 0x79ffff572000-0x79ffffa00000
FATAL: ThreadSanitizer: unexpectedly found incompatible memory layout.
FATAL: Please file a bug.

--
exit: 66
--
shard JSON output does not exist: /vol/worker/clangd-ubuntu-clang/clangd-ubuntu-tsan/build/tools/clang/tools/extra/clangd/unittests/./ClangdTests-Clangd Unit Tests-857188-16-21.json
********************


```

</details>

https://github.com/llvm/llvm-project/pull/106715