ima: Add ima policy related data to the ima namespace

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


CVE: NA

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Collate global variables describing the ima policy in one structure and
add it to the ima namespace. Collate setup data (parsed kernel boot
parameters) in a separate structure.

Per namespace policy is not yet properly set and it is not used. This
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>