LoongArch: Introduce the numa_memblks conversion

Commit 87482708 ("mm: introduce numa_memblks") has moved
numa_memblks from x86 to the generic code, but LoongArch was left out
of this conversion.

This patch introduces the generic numa_memblks for LoongArch.

In detail:
1. Enable NUMA_MEMBLKS (but disable NUMA_EMU) in Kconfig;
2. Use generic definition for numa_memblk and numa_meminfo;
3. Use generic implementation for numa_add_memblk() and its friends;
4. Use generic implementation for numa_set_distance() and its friends;
5. Use generic implementation for memory_add_physaddr_to_nid() and its
   friends.

Note: Disable NUMA_EMU because it needs more efforts and no obvious
demand now.

Tested-by: Binbin Zhou <zhoubinbin@loongson.cn>
Signed-off-by: Yuquan Wang <wangyuquan1236@phytium.com.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>