Revert "AMDGPU: enable 128-bit for local addr space under an option"

This reverts commit r329591.

It breaks various bots:
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-fast/builds/16516
http://lab.llvm.org:8011/builders/clang-ppc64be-linux/builds/17374
http://lab.llvm.org:8011/builders/clang-ppc64le-linux/builds/15992
http://lab.llvm.org:8011/builders/clang-ppc64be-linux-lnt
http://lab.llvm.org:8011/builders/clang-ppc64le-linux-lnt/builds/11251
...

llvm-svn: 329610
diff --git a/llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.cpp b/llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.cpp
index bf560a9..9f097cd 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.cpp
@@ -265,12 +265,10 @@
     return 512;
   }
 
-  if (AddrSpace == AS.FLAT_ADDRESS)
-    return 128;
-
-  if (AddrSpace == AS.LOCAL_ADDRESS ||
+  if (AddrSpace == AS.FLAT_ADDRESS ||
+      AddrSpace == AS.LOCAL_ADDRESS ||
       AddrSpace == AS.REGION_ADDRESS)
-    return ST->useDS128() ? 128 : 64;
+    return 128;
 
   if (AddrSpace == AS.PRIVATE_ADDRESS)
     return 8 * ST->getMaxPrivateElementSize();