Based on lwip_ethernetif.c skeleton file,
use init, receive and transfer
functionality of SMSC9220 Ethernet driver
for the lightweight IP stack.
Receive mechanism is interrupt driven.
HW buffer sizes:
Tx = 4608 bytes (MTU)
Rx = 10560 bytes
lwIP fine tuning:
mbed-os/features/FEATURE_LWIP/lwip-interface/lwip/src/include/lwip/opt.h
Change-Id: I0ea95650c65fb32cafb5c2d3dde11420c61dba66
Signed-off-by: Gabor Kertesz <gabor.kertesz@arm.com>