[Custom Ops] Add functional + out variant for scaled_fp4_quant (#34389)

Signed-off-by: tianrengao <terrygao87@gmail.com>

csrc/quantization/fp4/nvfp4_utils.cuh

@@ -18,6 +18,7 @@
 
 #include <cuda_runtime.h>
 #include <cuda_fp8.h>
+#include <utility>
 
 #include "../../cuda_vec_utils.cuh"
 
@@ -54,6 +55,18 @@ inline int computeEffectiveRows(int m) {
   return round_up(m, ROW_TILE);
 }
 
+// Compute the shape of the swizzled SF output tensor.
+// Returns (rounded_m, rounded_n / 4) where:
+//   rounded_m = round_up(m, 128)
+//   rounded_n = round_up(n / CVT_FP4_SF_VEC_SIZE, 4)
+inline std::pair<int64_t, int64_t> computeSwizzledSFShape(int64_t m,
+                                                          int64_t n) {
+  int64_t rounded_m = round_up(m, static_cast<int64_t>(128));
+  int64_t scale_n = n / CVT_FP4_SF_VEC_SIZE;
+  int64_t rounded_n = round_up(scale_n, static_cast<int64_t>(4));
+  return {rounded_m, rounded_n / 4};
+}
+
 // Convert 8 float32 values into 8 e2m1 values (represented as one uint32_t).
 inline __device__ uint32_t fp32_vec8_to_e2m1(float (&array)[8]) {
   uint32_t val;