plugin-loader: Removed unused path argument of load() method

Multiple additional search paths can be added with the add_path()
method.

src/libhydra/plugins/attr_sql/pool.c

@@ -1260,7 +1260,7 @@ int main(int argc, char *argv[])
 		fprintf(stderr, "integrity check of pool failed\n");
 		exit(SS_RC_DAEMON_INTEGRITY);
 	}
-	if (!lib->plugins->load(lib->plugins, NULL,
+	if (!lib->plugins->load(lib->plugins,
 			lib->settings->get_str(lib->settings, "pool.load", PLUGINS)))
 	{
 		exit(SS_RC_INITIALIZATION_FAILED);