[Inference/Feat] Add kvcache quantization support for FlashDecoding (#5656)

extensions/csrc/funcs/unary_functor.h

@@ -15,21 +15,6 @@
 namespace colossalAI {
 namespace funcs {
 
-template <typename T>
-inline __device__ void zero(T& dst) {
-  constexpr int WORDS = sizeof(T) / 4;
-  union {
-    T raw;
-    uint32_t words[WORDS];
-  } tmp;
-
-#pragma unroll
-  for (int ii = 0; ii < WORDS; ii++) {
-    tmp.words[ii] = 0u;
-  }
-  dst = tmp.raw;
-}
-
 // Note(LiuYang): As a retrieved table to check which operation is supported
 // already
 enum class UnaryOpType { kLog2Ceil = 0, kAbs, kSum };