support converting interfaces with parameters

test/basic/interface_func.v

@@ -1,7 +1,16 @@
 module top;
-    function bar;
+    localparam MULTIPLIER_1 = 7;
+    localparam MULTIPLIER_2 = 8;
+    function integer bar_1;
         input integer x;
-        bar = x * x;
+        bar_1 = x * x * MULTIPLIER_1;
     endfunction
-    initial $display(bar(3));
+    function integer bar_2;
+        input integer x;
+        bar_2 = x * x * MULTIPLIER_2;
+    endfunction
+    initial begin
+        $display(bar_1(3));
+        $display(bar_2(3));
+    end
 endmodule