dm integrity: log audit events for dm-integrity target

dm-integrity signals integrity violations by returning I/O errors
to user space. To identify integrity violations by a controlling
instance, the kernel audit subsystem can be used to emit audit
events to user space. We use the new dm-audit submodule allowing
to emit audit events on relevant I/O errors.

The construction and destruction of integrity device mappings are
also relevant for auditing a system. Thus, those events are also
logged as audit events.

Signed-off-by: Michael Weiß <michael.weiss@aisec.fraunhofer.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>