mm: Be allowed to alloc CDM node memory for MPOL_BIND

ascend inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4JMLR


CVE: NA
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CDM nodes should not be part of mems_allowed, However,
It must be allowed to alloc from CDM node, when mpol->mode was MPOL_BIND.

Signed-off-by: Lijun Fang <fanglijun3@huawei.com>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>