[BugFix] fix pre_reorder_triton_kernel default int32 issue (sgl-project#7814)

Author: Yuechguo

python/sglang/srt/layers/moe/ep_moe/kernels.py

@@ -236,7 +236,8 @@ def pre_reorder_triton_kernel(
 ):
     OutDtype = gateup_input_ptr.dtype.element_ty
 
-    src_idx = tl.program_id(0)
+    src_idx_int32 = tl.program_id(0)
+    src_idx = src_idx_int32.to(tl.int64)
     src2dst_ptr = src2dst_ptr + src_idx * topk
     topk_ids_ptr = topk_ids_ptr + src_idx * topk
     src_ptr = input_ptr + src_idx * hidden_size
@@ -255,7 +256,8 @@ def pre_reorder_triton_kernel(
             else:
                 scale = 1.0
 
-            dst_idx = tl.load(src2dst_ptr + idx)
+            dst_idx_int32 = tl.load(src2dst_ptr + idx)
+            dst_idx = dst_idx_int32.to(tl.int64)
             dst_ptr = gateup_input_ptr + dst_idx * hidden_size
             for start_offset in tl.range(0, hidden_size, BLOCK_SIZE):
                 offset = start_offset + vec