Add Nucleo H7A3ZI-Q and H755ZI-Q boards

[FFY00]

I based the board files on the H745ZI-Q file, as these two boards are the same hardware, just with a missing ethernet interface for the A3.

Please let me know if there's something else I need to add.

[FFY00]

After copying the board file to my project, so that I can use it right away, I am seeing this.

$ pio boards h7a3

Platform: atmelavr
==================================================================================
ID               MCU             Frequency    Flash    RAM    Name
---------------  --------------  -----------  -------  -----  ------------------
nucleo_h7a3zi_q  STM32H7A3ZIT6Q  280MHz       2MB      128KB  ST Nucleo H7A3ZI-Q

Platform: ststm32
==================================================================================
ID               MCU             Frequency    Flash    RAM    Name
---------------  --------------  -----------  -------  -----  ------------------
nucleo_h7a3zi_q  STM32H7A3ZIT6Q  280MHz       2MB      128KB  ST Nucleo H7A3ZI-Q

Which seems wrong, it is listed as atmelavr, and shows up as 128KB of RAM while in fact it has 1376KB. I believe my board definition is correct, is this a platformio bug?

[FFY00]

My RAM value was actually wrong, but the platform issue is still valid.

[rob4226]

Hello, thank you for making these board definitions. I am about to purchase a NUCLEO-H755ZI-Q board with the STM32H755ZI MCU but I don't see it listed in PlatformIO. Would I be able to use boards/nucleo_h755zi_q.json or is there a reason it hasn't been merged in? Thanks!