Revert "[mips][FastISel] Implement shift ops for Mips fast-isel."

This reverts commit r235194. It was causing a failure in FastISel buildbots
due to sign-extension issues.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235495 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed