mainline inclusion
from mainline-v5.19
commit f62b7626
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5OHOB
CVE: NA

--------------------------------

The content of LoongArch's compiler.h is trivial, with some unused
anywhere, so inline the definitions and remove the header.
Signed-off-by: NJun Yi <yijun@loongson.cn>
Signed-off-by: NHuacai Chen <chenhuacai@loongson.cn>