server : re-enable SWA speculative decoding (#14131)

ggml-ci

tools/server/server.cpp

@@ -2017,11 +2017,6 @@ struct server_context {
                 params_base.n_cache_reuse = 0;
                 SRV_WRN("%s\n", "cache_reuse is not supported by this context, it will be disabled");
             }
-
-            if (!params_base.speculative.model.path.empty()) {
-                SRV_ERR("%s\n", "err: speculative decode is not supported by this context");
-                return false;
-            }
         }
 
         return true;