[llvm] Add RV64 constraint to SRLIW (PR #69416)

[via llvm-commits]

llvmbot wrote:

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Failed to cherry-pick: 48dab523784252448dbd42e72f0048ee0463368

https://github.com/llvm/llvm-project/actions/runs/6790559354

Please manually backport the fix and push it to your github fork.  Once this is done, please add a comment like this:

`/branch <user>/<repo>/<branch>`

https://github.com/llvm/llvm-project/pull/69416