devlink: Unlock on error in dumpit()

This needs to unlock before returning.

Fixes: 544e7c33 ("net: devlink: Add support for port regions")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20201026080127.GB1628785@mwandaSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/core/devlink.c

@@ -4919,8 +4919,10 @@ static int devlink_nl_cmd_region_read_dumpit(struct sk_buff *skb,
 		index = nla_get_u32(info->attrs[DEVLINK_ATTR_PORT_INDEX]);
 
 		port = devlink_port_get_by_index(devlink, index);
-		if (!port)
-			return -ENODEV;
+		if (!port) {
+			err = -ENODEV;
+			goto out_unlock;
+		}
 	}
 
 	region_name = nla_data(attrs[DEVLINK_ATTR_REGION_NAME]);