drm/vc4: skeleton "read registers into debugfs" driver.

Signed-off-by: Eric Anholt <eric@anholt.net>
drm/vc4: Add some limited modesetting code.

This doesn't end up working out -- though I'd heard you could plug in
a paddr to the fb set command and it would use that instead of
allocating space itself, that doesn't appear to actually be the case.

Signed-off-by: Eric Anholt <eric@anholt.net>
drm/vc4: Add minimal GEM support.

With this I fired off a demo triangle from a hacked up version of
https://github.com/phire/hackdriver -- now to build an actually usable
interface.

This is totally insecure.  Don't use it.

Signed-off-by: Eric Anholt <eric@anholt.net>