llama: rwkv6: Use ggml_norm instead of ggml_group_norm

Co-authored-by: compilade <git@compilade.net>

Author: MollySophia

src/llama.cpp

@@ -9496,10 +9496,10 @@ static struct ggml_tensor * llm_build_time_mix_rwkv6(
     cur = ggml_view_1d(ctx, wkv_output, n_embed * n_tokens, 0);
     *wkv_state = ggml_view_1d(ctx, wkv_output, n_embed * head_size * n_seqs, n_embed * n_tokens * sizeof(float));
 
-    // ggml_group_norm considers groups in the third dimension.
-    cur = ggml_reshape_4d(ctx, cur, n_embed / head_count, 1, head_count, n_tokens);
-    cur = ggml_group_norm(ctx, cur, head_count, 64e-5f);
-    // Convert back to a regular vector.
+    // group norm with head_count groups
+    cur = ggml_reshape_3d(ctx, cur, n_embed / head_count, head_count, n_tokens);
+    cur = ggml_norm(ctx, cur, 64e-5f);
+    // Convert back to regular vectors.
     cur = ggml_reshape_2d(ctx, cur, n_embed, n_tokens);
     cur = ggml_add(ctx, ggml_mul(ctx, cur, layer->time_mix_ln), layer->time_mix_ln_b);