drm/vc4: tests: Use KUNIT_DEFINE_ACTION_WRAPPER

In order to pass functions to kunit_add_action(), they need to be of the
kunit_action_t type. While casting the function pointer can work, it
will break control-flow integrity.

vc4_mock already defines such a wrapper for drm_dev_unregister(), but it
involves less boilerplate to use the new macro, so replace the manual
implementation.

Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

drm/vc4: tests: mock: Use a kunit action to unregister DRM device

The *_mock_device functions allocate a DRM device that needs to be
released using drm_dev_unregister.

Now that we have a kunit release action API, we can switch to it and
don't require any kind of garbage collection from the caller.

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Maíra Canal <mairacanal@riseup.net>
Link: https://lore.kernel.org/r/20230728-kms-kunit-actions-rework-v3-8-952565ccccfe@kernel.org
Signed-off-by: Maxime Ripard <mripard@kernel.org>

drm/vc4: tests: Introduce a mocking infrastructure

In order to test the current atomic_check hooks we need to have a DRM
device that has roughly the same capabilities and layout that the actual
hardware. We'll also need a bunch of functions to create arbitrary
atomic states.

Let's create some helpers to create a device that behaves like the real
one, and some helpers to maintain the atomic state we want to check.

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Maíra Canal <mcanal@igalia.com>
Link: https://lore.kernel.org/r/20221123-rpi-kunit-tests-v3-17-4615a663a84a@cerno.tech
Signed-off-by: Maxime Ripard <maxime@cerno.tech>