p54usb: fix leaks at failure path in p54u_probe()

If p54u_load_firmware() fails, p54u_probe() does not deallocate
already allocated resources. The patch adds proper failure handling.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Acked-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/p54/p54usb.c

@@ -1053,6 +1053,10 @@ static int p54u_probe(struct usb_interface *intf,
 		priv->upload_fw = p54u_upload_firmware_net2280;
 	}
 	err = p54u_load_firmware(dev, intf);
+	if (err) {
+		usb_put_dev(udev);
+		p54_free_common(dev);
+	}
 	return err;
 }