zero out attn outputs during profile run

Signed-off-by: Varun Sundar Rabindranath <[email protected]>
Signed-off-by: Bill Nell <[email protected]>

Author: Varun Sundar Rabindranath

vllm/v1/attention/backends/mla/common.py

@@ -882,7 +882,7 @@ def forward(
 
         if attn_metadata is None:
             # Profiling run.
-            return output
+            return output.fill_(0)
 
         num_actual_toks = attn_metadata.num_actual_tokens