can: peak_usb: fix product-id endianness in error message

Make sure to use the USB device product-id stored in host-byte order in
a probe error message.

Also remove a redundant reassignment of the local usb_dev variable which
had already been used to retrieve the product id.

Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>