driver core: fw_devlink: Avoid spurious error message

fw_devlink can sometimes try to create a device link with the consumer
and supplier as the same device. These attempts will fail (correctly),
but are harmless. So, avoid printing an error for these cases. Also, add
more detail to the error message.

Fixes: 3fb16866 ("driver core: fw_devlink: Make cycle detection more robust")
Reported-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reported-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20230225064148.274376-1-saravanak@google.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/core.c

@@ -2046,9 +2046,9 @@ static int fw_devlink_create_devlink(struct device *con,
 			goto out;
 		}
 
-		if (!device_link_add(con, sup_dev, flags)) {
-			dev_err(con, "Failed to create device link with %s\n",
-				dev_name(sup_dev));
+		if (con != sup_dev && !device_link_add(con, sup_dev, flags)) {
+			dev_err(con, "Failed to create device link (0x%x) with %s\n",
+				flags, dev_name(sup_dev));
 			ret = -EINVAL;
 		}