According to the header in max730x it is licensed GPLv2.

Add a MODULE_LICENSE to avoid getting the kernel tainted.

Signed-off-by: Richard Röjfors <richard.rojfors@pelagicore.com>
---
diff --git a/drivers/gpio/max730x.c b/drivers/gpio/max730x.c
index c9bced5..6474577 100644
--- a/drivers/gpio/max730x.c
+++ b/drivers/gpio/max730x.c
@@ -242,3 +242,5 @@ int __devexit __max730x_remove(struct device *dev)
 	return ret;
 }
 EXPORT_SYMBOL_GPL(__max730x_remove);
+
+MODULE_LICENSE("GPL v2");