hw/arm: Add minimal support for the B-L475E-IOT01A board

hw/arm: Add minimal support for the B-L475E-IOT01A board

This commit adds a new B-L475E-IOT01A board using the STM32L475VG SoC
as well as a dedicated documentation file.
The implementation is derived from the Netduino Plus 2 machine.
There are no peripherals implemented yet, only memory regions.

Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Arnaud Minier <arnaud.minier@telecom-paris.fr>
Signed-off-by: Inès Varhol <ines.varhol@telecom-paris.fr>
Message-id: 20240108135849.351719-3-ines.varhol@telecom-paris.fr
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>