hw/arm/sbsa-ref: add "reg" property to DT cpu nodes

hw/arm/sbsa-ref: add "reg" property to DT cpu nodes

The sbsa-ref platform uses a minimal device tree to pass amount of memory
as well as number of cpus to the firmware. However, when dumping that
minimal dtb (with -M sbsa-virt,dumpdtb=<file>), the resulting blob
generates a warning when decompiled by dtc due to lack of reg property.

Add a simple reg property per cpu, representing a 64-bit MPIDR_EL1.

This also ends up being cleaner than having the firmware calculating its
own IDs for generating APCI.

Signed-off-by: Leif Lindholm <leif@nuviainc.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20200827124335.30586-1-leif@nuviainc.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>