ima: Add integrity inode related data to the ima namespace

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I49KW1


CVE: NA

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Add an iint tree to the ima namespace. Each namespace should track
operations on its objects separately. Per namespace iint tree is not
yet used, it will be done in the following patches.

Signed-off-by: Krzysztof Struczynski <krzysztof.struczynski@huawei.com>
Reviewed-by: Zhang Tianxing <zhangtianxing3@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>