qnap-poweroff: Fix license string

GPLv2+ is not a valid license string. Replace it with one that is.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Anton Vorontsov <anton@enomsg.org>
diff --git a/drivers/power/reset/qnap-poweroff.c b/drivers/power/reset/qnap-poweroff.c
index cecb317..37f56f7 100644
--- a/drivers/power/reset/qnap-poweroff.c
+++ b/drivers/power/reset/qnap-poweroff.c
@@ -113,4 +113,4 @@
 
 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
 MODULE_DESCRIPTION("QNAP Power off driver");
-MODULE_LICENSE("GPLv2+");
+MODULE_LICENSE("GPL v2");