Fix for Top K disabling (#480)

* Update gpttype_adapter.cpp

* use n_vocab instead of 32000 for when top k is off

gpttype_adapter.cpp

@@ -1312,7 +1312,7 @@ generation_outputs gpttype_generate(const generation_inputs inputs, generation_o
     }
     if (params.top_k < 1)
     {
-        params.top_k = 120; //to disable top_k we actually need to increase this value to a very high number
+        params.top_k = n_vocab; // all tokens in the vocabulary should be considered if top k is disabled
     }
     if (params.seed <= 0 || params.seed==0xFFFFFFFF)
     {