[Kimi-K3][AMD] Return KDA and MLA projection outputs directly (#50592)

Signed-off-by: Liuyinfeng01 <yinfeliu@amd.com>
Co-authored-by: Liuyinfeng01 <199041580+LiuYinfeng01@users.noreply.github.com>
Co-authored-by: Andreas Karatzas <akaratza@amd.com>

vllm/model_executor/layers/mamba/gdn/kimi_gdn_linear_attn.py

@@ -329,8 +329,7 @@ class KimiGatedDeltaNetAttention(GatedDeltaNetAttention):
         self,
         hidden_states: torch.Tensor,
         positions: torch.Tensor,
-        output: torch.Tensor,
-    ) -> None:
+    ) -> torch.Tensor:
         num_tokens = hidden_states.size(0)
         projected_qkvgfab = self.in_proj_qkvgfab(hidden_states)[0]
         if self.use_full_rank_gate:
@@ -375,7 +374,7 @@ class KimiGatedDeltaNetAttention(GatedDeltaNetAttention):
             core_attn_out=core_attn_out,
         )
         core_attn_out = rearrange(core_attn_out, "1 n h d -> n (h d)")
-        output[:] = self.o_proj(core_attn_out)[0]
+        return self.o_proj(core_attn_out)[0]
 
     @eager_break_during_capture
     def _forward(