share_pool: Fix flags conflict

ascend inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4SON8


CVE: NA

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MAP_SHARE_POOL and MAP_FIXED_NOREPLACE have the same value.
Redefine MAP_SHARE_POOL to fix it.

Signed-off-by: Wang Wensheng <wangwensheng4@huawei.com>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>