[X86] Remove SplitBinaryOpsAndApply and use SplitOpsAndApply by adding curly braces around the ops.

Summary: Unless you were intentionally avoiding this syntax? I saw you mentioned makeArrayRef in your commit that added SplitOpsAndApply.

Reviewers: RKSimon

Reviewed By: RKSimon

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D44403

llvm-svn: 327418