Since loongson3_smp_ops is not used in LoongArch anymore, let's remove
it for cleanup.

Fixes: f2ac457a ("LoongArch: Add CPU definition headers")
Signed-off-by: NYanteng Si <siyanteng@loongson.cn>
Signed-off-by: NHuacai Chen <chenhuacai@loongson.cn>