[llvm] [X86] Remove outdated comment (PR #133743)

[Evgenii Kudriashov via llvm-commits]

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@@ -371,8 +371,7 @@ def FeatureMOVRS   : SubtargetFeature<"movrs", "HasMOVRS", "true",
                            "Enable MOVRS", []>;
 
 // Ivy Bridge and newer processors have enhanced REP MOVSB and STOSB (aka
-// "string operations"). See "REP String Enhancement" in the Intel Software
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e-kud wrote:

Maybe keep the chapter name but specify the revision or the publication date?

https://github.com/llvm/llvm-project/pull/133743