hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5O5RQ
CVE: NA

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Notice that in sp_unshare_uva(), for authentication check, comparison
between current->tgid and spa->applier is well enough. There is no need
to check current->mm against spa->mm.

Other redundant cases:
- find_spg_node_by_spg() will never return NULL in current use context;
- spg_info_show() will not come across a group with id 0.

Therefore, delete these redundant paths.
Signed-off-by: NGuo Mengqi <guomengqi3@huawei.com>