Revert "hack: findTotalEltsLessThanTarget_v2 support arbitrary arr len"

This reverts commit 8c719e6.

Author: fzyzcjy

csrc/fused_moe/cutlass_backend/cutlass_fused_moe_kernels.cuh

@@ -884,18 +884,18 @@ __device__ inline int64_t findTotalEltsLessThanTarget_v1(T const* sorted_indices
 
 template <class T>
 __device__ inline int64_t findTotalEltsLessThanTarget_v2(T const* sorted_indices, int64_t const arr_length, T const target) {
-  // constexpr int ARR_LENGTH_CONST = 128;
-  // if (arr_length != ARR_LENGTH_CONST) {
-  //     asm("trap;");
-  // }
+  constexpr int ARR_LENGTH_CONST = 128;
+  if (arr_length != ARR_LENGTH_CONST) {
+      asm("trap;");
+  }
 
   constexpr unsigned full_mask = 0xffffffffu;
   constexpr int WARP_SZ = 32;
   const int lane_id = threadIdx.x & (WARP_SZ - 1);
 
   int local_count = 0;
 #pragma unroll
-  for (int k = 0; k < arr_length / WARP_SZ; ++k) {
+  for (int k = 0; k < ARR_LENGTH_CONST / WARP_SZ; ++k) {
     const int idx = lane_id + k * WARP_SZ;
     T v = sorted_indices[idx];
     local_count += (v < target) ? 1 : 0;