net: usb: cdc_ether: add u-blox 0x1313 composition.

Add CDC-ECM support for LARA-R6 01B.

The new LARA-R6 product variant identified by the "01B" string can be
configured (by AT interface) in three different USB modes:
* Default mode (Vendor ID: 0x1546 Product ID: 0x1311) with 4 serial
interfaces
* RmNet mode (Vendor ID: 0x1546 Product ID: 0x1312) with 4 serial
interfaces and 1 RmNet virtual network interface
* CDC-ECM mode (Vendor ID: 0x1546 Product ID: 0x1313) with 4 serial
interface and 1 CDC-ECM virtual network interface
The first 4 interfaces of all the 3 configurations (default, RmNet, ECM)
are the same.

In CDC-ECM mode LARA-R6 01B exposes the following interfaces:
If 0: Diagnostic
If 1: AT parser
If 2: AT parser
If 3: AT parset/alternative functions
If 4: CDC-ECM interface

Signed-off-by: Davide Tronchin <davide.tronchin.94@gmail.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>