The current LoongArch kernel stack is padded as if obeying the MIPS o32
calling convention (32 bytes), signifying the port's MIPS lineage but no
longer making sense. Remove the padding for clarity.
Reviewed-by: NWANG Xuerui <git@xen0n.name>
Signed-off-by: NJinyang He <hejinyang@loongson.cn>
Signed-off-by: NHuacai Chen <chenhuacai@loongson.cn>