hw/arm/sbsa-ref: Enable CPU cluster on ARM sbsa machine

hw/arm/sbsa-ref: Enable CPU cluster on ARM sbsa machine

Enable CPU cluster support on SbsaQemu platform, so that users can
specify a 4-level CPU hierarchy sockets/clusters/cores/threads. And
this topology can be passed to the firmware through /cpus/topology
Device Tree.

Signed-off-by: Xiong Yining <xiongyining1480@phytium.com.cn>
Reviewed-by: Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org>
Reviewed-by: Leif Lindholm <quic_llindhol@quicinc.com>
Message-id: 20240607103825.1295328-2-xiongyining1480@phytium.com.cn
Tested-by: Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>