keys: Allow to set key domain tag separately from the key type

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


CVE: NA

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Add KEY_ALLOC_DOMAIN_* flags so that the key domain tag can be
specified on the key creation. This is done to separate the
key domain setting from the key type.

If applied to the keyring, it will set the requested domain tag for
every key added to that keyring.

IMA uses the existing key_type_asymmetric for appraisal, but also has
to specify the key domain to bind appraisal key with the ima namespace.

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