AMDGPU: Delete more dead code

Remove dead code from r600 intrinsic removal.
Remove unset members, rename StackSize to be less ambiguous.

llvm-svn: 276436
diff --git a/llvm/lib/Target/AMDGPU/R600ControlFlowFinalizer.cpp b/llvm/lib/Target/AMDGPU/R600ControlFlowFinalizer.cpp
index d5bda4a..4e106bd 100644
--- a/llvm/lib/Target/AMDGPU/R600ControlFlowFinalizer.cpp
+++ b/llvm/lib/Target/AMDGPU/R600ControlFlowFinalizer.cpp
@@ -680,7 +680,7 @@
             .addImm(Alu->getOperand(8).getImm());
         Alu->eraseFromParent();
       }
-      MFI->StackSize = CFStack.MaxStackSize;
+      MFI->CFStackSize = CFStack.MaxStackSize;
     }
 
     return false;