bootloader: Use stage2_args:arguments_count

The code probably doesn't work correctly yet though,
I believe only the last line will be taken into account.

src/system/boot/loader/load_driver_settings.cpp

@@ -116,7 +116,7 @@ add_stage2_driver_settings(stage2_args* args)
 {
 	// TODO: split more intelligently
 	for (const char** arg = args->arguments;
-			arg != NULL && arg[0] != NULL; arg++) {
+			arg != NULL && args->arguments_count-- && arg[0] != NULL; arg++) {
 		dprintf("adding args: '%s'\n", arg[0]);
 		add_safe_mode_settings((char*)arg[0]);
 	}