Platforms/RaspberryPi: add CM4 and 400 as BCM2711 designs

Like the Pi 4B, the 3GB/4GB choices apply to it as well.

Values taken from
https://www.raspberrypi.org/documentation/hardware/raspberrypi/revision-codes/README.md



Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>
Reviewed-by: Samer El-Haj-Mahmoud <Samer.El-Haj-Mahmoud@arm.com>