cros_ec: Don't return error when checking command version

With this patch, cros_ec_query_all() does not return an error if it
fails to check for MKBP events support. Instead, the EC device structure
indicates that it does not support MKBP events (mkbp_event_supported
field) and cros_ec_query_all() returns 0.
Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
Signed-off-by: Benson Leung <bleung@chromium.org>

drivers/platform/chrome/cros_ec_proto.c

@@ -371,6 +371,8 @@ int cros_ec_query_all(struct cros_ec_device *ec_dev)
 	else
 		ec_dev->mkbp_event_supported = 1;
 
+	ret = 0;
+
 exit:
 	kfree(proto_msg);
 	return ret;