The BCM2711 has a separate driver for the v3d, and thus we can't call
into any of the driver entrypoints that rely on the v3d being there.

Let's add a bunch of checks and complain loudly if that ever happen.
Reviewed-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20220610115149.964394-15-maxime@cerno.tech