Fix top_p and top_k args in sglang for shortfin

Author: stbaione

python/sglang/lang/ir.py

@@ -132,16 +132,11 @@ def to_shortfin_kwargs(self):
             "temperature": self.temperature,
         }
 
-        top_p = self.top_p
-        if top_p == 1.0:
-            top_p = None
-
-        top_k = self.top_k
-        if top_k == -1:
-            top_k = None
-
-        kwargs["sampling_params"]["top_p"] = top_p
-        kwargs["sampling_params"]["top_k"] = top_k
+        top_p, top_k = self.top_p, self.top_k
+        if top_p != 1.0:
+            kwargs["sampling_params"]["top_p"] = top_p
+        if top_k != -1:
+            kwargs["sampling_params"]["top_k"] = top_k
 
         return kwargs