[llvm] [AArch64] Use vecshiftL64 instead of vecshiftR64 to match scalar SLI imm. (PR #139904)

[via llvm-commits]

llvmbot wrote:

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Failed to cherry-pick: e7e4d99c586399758e6ddb76fb358c2dcccfae36

https://github.com/llvm/llvm-project/actions/runs/15041878331

Please manually backport the fix and push it to your github fork.  Once this is done, please create a [pull request](https://github.com/llvm/llvm-project/compare)

https://github.com/llvm/llvm-project/pull/139904