LoongArch: Parse MADT to get multi-processor information

mainline inclusion
from mainline-v6.0-rc1
commit e9e7ff16
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5OHOB


CVE: NA

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Parse MADT to get multi-processor information, in order to fix the boot
problem and cpu-hotplug problem for SMP platform.

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>