bug fixes and enharcement to gemm reductionK fusion (#682)

* add two missing files

* fix bunch of bugs of gemm-reducek fusion and add a device interface

* small changes

Co-authored-by: Haicheng Wu <haichengw@nvidia.com>

include/cutlass/epilogue/threadblock/epilogue_gemm_k_reduction.h

@@ -149,13 +149,12 @@ public:
 
       CUTLASS_PRAGMA_UNROLL
       for (int i = 0; i < kIterations / 4; ++i) {
-        ElementOutput tmp;
+        ElementOutput *source_ptr = reinterpret_cast<ElementOutput *>(&source);
         cutlass::arch::global_load<ElementOutput, sizeof(ElementOutput)>(
-                                                  tmp,
+                                                  source_ptr[i],
                                                   (void *)(pointer_ + i * 32),
                                                   guard[i] && LoadForSerialSplitK);
 
-        source[i] = tmp;
       }
 
       FragmentAccumulator sum = gemm_k_with_reduction_accumulation;