hw/arm: Add i.MX 8M Plus EVK board

hw/arm: Add i.MX 8M Plus EVK board

As a first step, implement the bare minimum: CPUs, RAM, interrupt controller,
serial. All other devices of the A53 memory map are represented as
TYPE_UNIMPLEMENTED_DEVICE, i.e. the whole memory map is provided. This allows
for running Linux without it crashing due to invalid memory accesses.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Message-id: 20250223114708.1780-5-shentey@gmail.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
[PMM: drop 'static const' from serial_table[] definition to avoid
 compile failure on GCC 7.5]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>