MPS2 CM3DS ethernet fix packet bug

The function smsc9220_receive_by_chunks loads data from the Ethernet port.
It is expected to return the Ethernet frame without the 4 CRC bytes.
However, it is required to call the Ethernet data port register (32-bit)
an amount equal to the number of frame words (including the 4 CRC bytes)
to pop all frame words. The current code doesn't call the register for the
last word (which has CRC data). This causes subsequent calls to have this
missed word at the beginning. The impact of this is huge as the high level
API is getting fed wrong data. The fix adds one additional call to the data
port register.

Author: Rami Elkhatib

targets/TARGET_ARM_SSG/TARGET_CM3DS_MPS2/device/drivers/smsc9220_eth_drv.c

@@ -1060,6 +1060,7 @@ uint32_t smsc9220_receive_by_chunks(const struct smsc9220_eth_dev_t* dev,
     }
 
     empty_rx_fifo(dev, (uint8_t *)data, packet_length_byte);
+    (void) (register_map->rx_data_port); /* Discard last word (CRC) */
     dev->data->current_rx_size_words = 0;
     return packet_length_byte;
 }