LoongArch: Fix shared cache size calculation

mainline inclusion
from mainline-v5.19
commit 1aea29d7
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5OHOB


CVE: NA

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Current calculation of shared cache size is from the node (die) scope,
but we hope 'lscpu' to show the shared cache size of the whole package
for multi-die chips (e.g., Loongson-3C5000L, which contains 4 dies in
one package). So fix it by multiplying nodes_per_package.

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