nouveau: Add framebuffer modifier support

nouveau: Add framebuffer modifier support

This adds support for framebuffer modifiers to Nouveau. This will be
used by the Tegra driver to share metadata about the format of buffers
(such as the tiling mode or compression).

Changes in v2:
- remove unused parameters to nouveau_buffer_create()
- move format modifier query code to nvc0 backend
- restrict format modifiers to 2D textures
- implement ->query_dmabuf_modifiers()

Changes in v4:
- add UAPI include path on meson builds

Changes in v5:
- remove unnecessary includes

Acked-by: Emil Velikov <emil.velikov@collabora.com>
Tested-by: Andre Heider <a.heider@gmail.com>
Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: Thierry Reding <treding@nvidia.com>