mm/mempolicy: check preferred_node rather than nodes for MPOL_PREFERRED

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8O41A



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Commit b27abacc ("mm/mempolicy: add MPOL_PREFERRED_MANY for multiple
preferred nodes") add MPOL_PREFERRED_MANY which will return -1 if page
node id is not in nodes. However this is useful for linux-v5.15 since
commit 269fbe72 ("mm/mempolicy: use unified 'nodes' for
bind/interleave/prefer policies") already unify bind/prefer policies.
While this patch does not exists during backport. To fix this, drop
checking v.nodes for prefer.

Fixes: 52e5df72 ("mm/mempolicy: add MPOL_PREFERRED_MANY for multiple preferred nodes")
Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>