[X86] Clean up test/CodeGen/X86/2006-03-02-InstrSchedBug.ll

Summary:
Migrated from grep to FileCheck.
Re-indented code, removed boilerplate comments.
Added 'entry' label at beginning of basic block.

Patch by Jorge Gorbe!

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D30320

llvm-svn: 296280