[dv/kmac] Fix kmac TL integrity error failure
[dv/kmac] Fix kmac TL integrity error failure

When kmac TL integrity error triggers, kmac will lock its internal
states and also lock `cfg_regwen` register. Because the `cfg_regwen` is
a `ro` register, RAL model won't lock its lockable registers
automatically.
So I separate out a task in common sequence, and override it in
kmac_common_seq to lock the lockable regs
immediately after tl integrity error is triggered.

Signed-off-by: Cindy Chen <399ad771a111eac8923348b1e2af093034e5d4f1@opentitan.org>

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