hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4O31I

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

Move x86's pmem.c into nvdimm, and rename X86_PMEM_LEGACY_DEVICE to
PMEM_LEGACY_DEVICE, also add PMEM_LEGACY to control the built of
nd_e820.o, then the code could be reused by other architectures.

Note，this patch fixs the nd_e820.c build introduced by commit 2499317e
("arm64: Revert feature: Add memmap parameter and register pmem").
Signed-off-by: NZhuling <zhuling8@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>