Regularize WIZnet boards

[fasteddy516]

This regularizes the 3 existing WIZnet board definitions as requested by @dhalbert in PR #10179. Firmware for all boards builds successfully, and was tested on the corresponding board using this HTTP Server + Websocket script which utilizes the new W5K_ pin aliases. Please note the following:

1. The RP2040-based boards have #pragma once declarations in both .h files. The RP2350 board does not. I suspect this ultimately makes no difference in these cases, but I'd like to make them all the same in the 'right' way. Do I make sure #pragma once is in all of the .h files, or remove it from all?

2. All boards now have the W5K_ pin aliases as applied to the W5500-EVB-Pico2 in PR Add WIZnet W5500-EVB-Pico2 board #10179.

3. The pin aliases added by @jepler in commit 40cc500 have been removed, as these labels are not on the board silkscreen and were only ever defined for 1 of the 3 existing boards.

4. The RP2040-based boards both had CIRCUITPY_HOST_USB disabled by @timchinowsky in Commit 8377a74. I assume this was done for a good reason and left it in place. I did not apply this to the RP2350 board.

5. All boards already had DEFAULT_SPI_ and DEFAULT_UART_ defined in mpconfigboard.h. I've left these in place for now, but can remove them if necessary.

6. Since those defaults are currently in place, I've added SPI and UART to pins.c for the RP2040-based boards. The RP2350 board already had them. Again, these can be removed if necessary.

For the default peripherals, I was reluctant to remove any of them as it could "break" existing code. (I'm also pretty confident - after spending way too much time comparing the various datasheets and pinout diagrams - that those defaults are correct, but I'm happy to defer to the general consensus)

[dhalbert]

Re 1: all .h should have #pragma once.

[dhalbert]

Thanks, and thanks for your patience amid all the discussion.