enable default driver

see OpenSC
1a972920f0dd4959bd6ec3c4cddef2d98e6009a8

npa/src/scutil.c

@@ -42,6 +42,7 @@ int initialize(int reader_id, int verbose,
     }
 
     (*ctx)->debug = verbose;
+	(*ctx)->enable_default_driver = 1;
 
     reader_count = sc_ctx_get_reader_count(*ctx);