hw/misc/iotkit-sysinfo.c: Implement SYS_CONFIG1 and IIDR

hw/misc/iotkit-sysinfo.c: Implement SYS_CONFIG1 and IIDR

For SSE-300, the SYSINFO register block has two new registers:

 * SYS_CONFIG1 indicates the config for a potential CPU2 and CPU3;
   since the SSE-300 can only be configured with a single CPU it
   is always zero

 * IIDR is the subsystem implementation identity register;
   its value is set by the SoC integrator, so we plumb this in from
   the armsse.c code as we do with SYS_VERSION and SYS_CONFIG

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210219144617.4782-11-peter.maydell@linaro.org