debug: compare only first HD_CHUNK values

tests/unit/test_fmha_6warp_tma_multirow_multitile.cu

@@ -180,8 +180,9 @@ static int test_single(int T, int s_k, int n_h = 1, int batch = 1) {
             o_ref, nullptr, HD, T, s_k, SCALE);
 
         float cs = 0, na = 0, nb = 0;
+        int check_hd = HD_CHUNK;  // Only check first hd_chunk values (for partial debug)
         for (int t = 0; t < T; t++) {
-            for (int d = 0; d < HD; d++) {
+            for (int d = 0; d < check_hd; d++) {
                 float a = bf16_to_f32_host(h_o[h * MAX_T * HD + t * HD + d]);
                 float b = o_ref[t * HD + d];
                 if (fabsf(b) > 1e-4f) { cs += a * b; na += a * a; nb += b * b; }