Add missing #include directive to get access to cutlass::epilogue::th…

…read::ScaleType. (#925)

Currently, the `LinearCombinationClamp` header file is not standalone,
and must have the definition of `cutlass::epilogue::thread::ScaleType`
already available when it is `#include`d.

include/cutlass/epilogue/thread/linear_combination_clamp.h

@@ -40,6 +40,7 @@
 #include "cutlass/array.h"
 #include "cutlass/functional.h"
 #include "cutlass/numeric_conversion.h"
+#include "cutlass/epilogue/thread/scale_type.h"
 
 /////////////////////////////////////////////////////////////////////////////////////////////////