drm/vc4: tests: Fix UAF in the mock helpers

The VC4 mock helpers allocate the CRTC, encoders and connectors using a
call to kunit_kzalloc(), but the DRM device they are attache to survives
for longer than the test itself which leads to use-after-frees reported
by KASAN.

Switch to drmm_kzalloc to tie the lifetime of these objects to the main
DRM device.

Fixes: f759f5b53f1c ("drm/vc4: tests: Introduce a mocking infrastructure")
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Closes: https://lore.kernel.org/all/CA+G9fYvJA2HGqzR9LGgq63v0SKaUejHAE6f7+z9cwWN-ourJ_g@mail.gmail.com/
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Reviewed-by: Maíra Canal <mcanal@igalia.com>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231024105640.352752-1-mripard@kernel.org

drm/vc4: Switch to container_of_const

container_of_const() allows to preserve the pointer constness and is
thus more flexible than inline functions.

Let's switch all our instances of container_of() to
container_of_const().

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://lore.kernel.org/r/20221207-rpi-hdmi-improvements-v3-1-bdd54f66884e@cerno.tech
Signed-off-by: Maxime Ripard <maxime@cerno.tech>

drm/vc4: tests: Add unit test suite for the PV muxing

The HVS to PixelValve muxing code is fairly error prone and has a bunch
of arbitrary constraints due to the hardware setup.

Let's create a test suite that makes sure that the possible combinations
work and the invalid ones don't.

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-v3-19-4615a663a84a@cerno.tech
Signed-off-by: Maxime Ripard <maxime@cerno.tech>

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>