USB: fix __must_check warnings in drivers/usb/input/

Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/input/yealink.c b/drivers/usb/input/yealink.c
index 7b45fd3..7291e7a 100644
--- a/drivers/usb/input/yealink.c
+++ b/drivers/usb/input/yealink.c
@@ -971,7 +971,7 @@
 			DRIVER_VERSION, sizeof(DRIVER_VERSION));
 
 	/* Register sysfs hooks (don't care about failure) */
-	sysfs_create_group(&intf->dev.kobj, &yld_attr_group);
+	ret = sysfs_create_group(&intf->dev.kobj, &yld_attr_group);
 	return 0;
 }