W5500 LwIp binding

W5500 is used in MAC RAW mode. Hardware address filtering is switched off (this important if you are intended to use it as one of bridge interfaces) Interrupts are used only for RECV signal. Uses FreeRTOS. Tested with STM32.

How to use

1. Patch your LwIp tree with files from external_libs/lwip/port/FreeRTOS folder
2. Implement your low level init (SPI, GPIO, NVIC, clocks, etc.) and low level IO functions in device/wizchip/wizchip_port.c
3. Check interrupt handler example in app/interrupts.c. Change in accordance with your platform and GPIO setup (i.e. external interrupt number and so on)
4. Call lwipInit() in your main function.