clients/simple-dmabuf-drm: add freedreno support alongside intel

abstract drm specific bits to struct drm_device and support running on
freedreno. introduce 'modifier' event.

v2: rebase to master, deprecate 'format' event.

Signed-off-by: Varad Gautam <varad.gautam@collabora.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
3 files changed