[mlir] [llvm] fix linking on riscv64 (PR #74167)

[Brad Smith via llvm-commits]

brad0 wrote:

> @abrachet The line I'm uncommenting was originally commented out by your change https://reviews.llvm.org/D137799 maybe you have something to say about the rationale

Looking at the overall diff it looks like that might have been an unrelated change that snuck in and no one noticed.

https://github.com/llvm/llvm-project/pull/74167