drm/nouveau/disp: add acquire_dac()

- preparing to move protocol-specific args out of acquire() again
- avoid re-acquiring acquired output, will matter when enforced later
- this one is basically just a rename

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Acked-by: Danilo Krummrich <me@dakr.org>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230919220442.202488-13-lyude@redhat.com