net: usb: cdc_ether: use usb.h macros whenever possible

Use USB_DEVICE_AND_INTERFACE_INFO and USB_VENDOR_AND_INTERFACE_INFO
macros to reduce boilerplate.

Signed-off-by: Fabio Porcedda <fabio.porcedda@gmail.com>
Acked-by: Oliver Neukum <oliver@neukum.org>
Signed-off-by: David S. Miller <davem@davemloft.net>