Verilog Ethernet Integration Steps

[mkdigitals]

The road-map from now on is (the order might change between some steps, since not all of them are depended to each other):
- Add LWIP to the current cli-test, with necessary functions filled with dummy functionalities.
- err_t vif_init(struct netif *netif)
- err_t vif_link_output(struct netif *netif, struct pbuf *p)
- err_t vif_output(struct netif *netif, struct pbuf *p, ip_addr_t *ipaddr)
- err_t vif_input(struct netif *netif)
- Add test options to current cli-test interface to manipulate the Lwip initialization settings, and trigger some test stimulus.
- Tie the output and input functions to the MAC (This might require some modifications on MAC)
- Test and debug the system using the current built-in loop-back in the MAC.
- Reroute the i2c interface to the PHY - test first using the current i2c functionality.
- Tie the init function to PHY control.
- Test the network on PHY loop-back. (I assume PHY has loop-back functionality).
- Test the network on Hardware tied to a PC. The tests beyond this point are to be evaluated.

[mkdigitals]

last push : https://github.com/planvtech/robo-v-mcu-demo PROJ-11
TCP-IP was a bit too heavy for the system, I kept hitting memory overflow issues during compile time even though I reduced the functionalities. So I decided to change to UDP. LWIP is now calling the functions which are meant to be tied to the mac. Had to do a very small change in udma_uart_driver.c : Any printf operation was causing a stack overflow when called before the task scheduler; realized it is because of a semophore being taken for a short duration in putchar(), but during the semaphore being taken, putchar() is being called again and this was causing a runtime error during the LWIP initialization stage, so I made a change to release the semaphore after accessing to uart peripheral.

[vmayoral]

Closing in here for now. Follows from #39.

Thanks a lot for the effort @mkdigitals.