Fix the enumerator names for ShuffleKind to match tho coding standards,
and make its comments doxygen comments.

llvm-svn: 171688
diff --git a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
index 8a699af..9cc1b18 100644
--- a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
+++ b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
@@ -204,7 +204,7 @@
 unsigned X86TTI::getShuffleCost(ShuffleKind Kind, Type *Tp, int Index,
                                 Type *SubTp) const {
   // We only estimate the cost of reverse shuffles.
-  if (Kind != Reverse)
+  if (Kind != SK_Reverse)
     return TargetTransformInfo::getShuffleCost(Kind, Tp, Index, SubTp);
 
   std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(Tp);