[AMDGPU] Turn on the new waitcnt insertion pass. Adjust tests.

-enable-si-insert-waitcnts=1 becomes the default
-enable-si-insert-waitcnts=0 to use old pass

Differential Revision: https://reviews.llvm.org/D33730

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@304551 91177308-0d34-0410-b5e6-96231b3b80d8
22 files changed