drm/nouveau/disp/nv50-: simplify definition of overlay channels

Introduces a new method of defining channels available from the display,
common to all channel types, allowing for more flexibility in available
channel types/counts, and reducing the amount of boiler-plate required.

This will be required to support Volta.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
23 files changed