nvme-hwmon: Return error code when registration fails

The hwmon pointer wont be NULL if the registration fails. Though the
exit code path will assign it to ctrl->hwmon_device. Later
nvme_hwmon_exit() will try to free the invalid pointer. Avoid this by
returning the error code from hwmon_device_register_with_info().

Fixes: ed7770f6 ("nvme/hwmon: rework to avoid devm allocation")
Signed-off-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/host/hwmon.c

@@ -248,6 +248,7 @@ int nvme_hwmon_init(struct nvme_ctrl *ctrl)
 	if (IS_ERR(hwmon)) {
 		dev_warn(dev, "Failed to instantiate hwmon device\n");
 		kfree(data);
+		return PTR_ERR(hwmon);
 	}
 	ctrl->hwmon_device = hwmon;
 	return 0;