drivers/gpio/max730x.c: add license macro

According to the header in max730x it is licensed GPLv2.

Add a MODULE_LICENSE to avoid getting the kernel tainted.

[w.sang@pengutronix.de: add MODULE_AUTHOR and MODULE_DESCRIPTION also]
Signed-off-by: Richard Röjfors <richard.rojfors@pelagicore.com>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/gpio/max730x.c b/drivers/gpio/max730x.c
index c9bced5..4a7d662 100644
--- a/drivers/gpio/max730x.c
+++ b/drivers/gpio/max730x.c
@@ -242,3 +242,7 @@
 	return ret;
 }
 EXPORT_SYMBOL_GPL(__max730x_remove);
+
+MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts");