LoongArch: Add atomic/locking headers

mainline inclusion
from mainline-v5.19-rc1
commit 5b0b14e5
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5OHOB


CVE: NA

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Add common headers (atomic, bitops, barrier and locking) for basic
LoongArch support.

Reviewed-by: WANG Xuerui <git@xen0n.name>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>