Adds commented tensor declarations for mask and bias

Includes placeholder tensor declarations for future mask and bias support in the backward kernel computation. These commented lines prepare the codebase for upcoming attention mask and bias functionality.

Author: LoserCheems

csrc/src/flash_bwd_kernel.h

@@ -322,6 +322,8 @@ inline __device__ void compute_dq_dk_dv_1colblock(const Params &params, const in
     Tensor tSrK = thr_mma_sdp.partition_fragment_B(sK);                                         // (MMA, MMA_N, MMA_K)
     Tensor tdPrdO = thr_mma_sdp.partition_fragment_A(sdO);                                      // (MMA, MMA_N, MMA_K)
     Tensor tdPrV = thr_mma_sdp.partition_fragment_B(sV);                                        // (MMA, MMA_N, MMA_K)
+    // Tensor tSrMask = partition_fragment_C(tiled_mma_sdp, Shape<Int<kBlockM>, Int<kBlockN>>{});  // (MMA, MMA_M, MMA_N)
+    // Tensor tSrBias = partition_fragment_C(tiled_mma_sdp, Shape<Int<kBlockM>, Int<kBlockN>>{});  // (MMA, MMA_M, MMA_N)
 
     typename Kernel_traits::TiledMmadKV tiled_mma_dkv;
     auto thr_mma_dkv = tiled_mma_dkv.get_thread_slice(tidx);