net: asix: add support for the Sitecom LN-028 USB adapter

Just another AX88178-based 10/100/1000 USB-to-Ethernet dongle. This one
shows up in lsusb as: "Sitecom Europe B.V. LN-028 Network USB 2.0 Adapter".

Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Cc: Francois Romieu <romieu@fr.zoreil.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-usb@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>