Revert r299536. [AMDGPU] SDWA peephole: enable by default.

Reason: breaks multiple bots:

http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-fast/builds/3988
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-bootstrap/builds/1173

Original Review URL: https://reviews.llvm.org/D31671



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@299583 91177308-0d34-0410-b5e6-96231b3b80d8
44 files changed