Add logic cpu index input parameter for function cpu_by_arch_id,
CPUState::cpu_index is logic cpu slot index for possible_cpus.
At the same time it is logic index with LoongsonIPICommonState::IPICore,
here hide access for CPUState::cpu_index directly, it comes from
function cpu_by_arch_id().
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Reviewed-by: Bibo Mao <maobibo@loongson.cn>