[diffusion] multi-platform: support diffusion on amd and fix encoder loading on MI325 (#13760)

Co-authored-by: Sabre Shao <sabre.shao@amd.com>
Co-authored-by: Yusheng (Ethan) Su <yushengsu.thu@gmail.com>
Co-authored-by: Hubert Lu <Hubert.Lu@amd.com>
Co-authored-by: xsun <sunxiao04@gmail.com>

python/sglang/multimodal_gen/runtime/models/dits/causal_wanvideo.py

@@ -87,6 +87,7 @@ class CausalWanSelfAttention(nn.Module):
             causal=False,
             supported_attention_backends=(
                 AttentionBackendEnum.FA,
+                AttentionBackendEnum.AITER,
                 AttentionBackendEnum.TORCH_SDPA,
             ),
         )