[common] Add max_t support for KV in THD (#1370)

add max_t for KV
Signed-off-by: Charlene Yang <8636796+cyanguwa@users.noreply.github.com>

transformer_engine/common/fused_attn/fused_attn_f16_arbitrary_seqlen.cu

@@ -661,6 +661,7 @@ void fused_attn_arbitrary_seqlen_bwd_impl(
 
       if (is_ragged && cudnn_runtime_version >= 90600) {
         sdpa_backward_options.set_max_total_seq_len_q(s_q);
+        sdpa_backward_options.set_max_total_seq_len_kv(s_kv);
       }
 
       if (cudnn_runtime_version >= 90200 && window_size_left != -1) {