drm/nouveau/disp: add common channel class handling

Replaces a bunch of unnecessarily duplicated boilerplate in per-chipset
code with a simpler, common, implementation.

Channel "awaken" notify code is completely gone for now. KMS has never
made use of it so far, and event notify handling is about to be changed
in general anyway.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drm/nouveau/kms/nv50-: fix case where notifier buffer is at offset 0

VRAM offset 0 is a valid address, triggered on GA102.

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

drm/nouveau/kms/nv50-: use NVIDIA's headers for wimm update()

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>

drm/nouveau/kms/nv50-: use NVIDIA's headers for wimm point()

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>

drm/nouveau/kms/nv50-: convert wimm update() to new push macros

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>

drm/nouveau/kms/nv50-: convert wimm point() to new push macros

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>

drm/nouveau/kms/gv100-: fix spurious window immediate interlocks

Cursor position updates were accidentally causing us to attempt to interlock
window with window immediate, and without a matching window immediate update,
NVDisplay could hang forever in some circumstances.

Fixes suspend/resume on (at least) Quadro RTX4000 (TU104).

Reported-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drm/nouveau/kms/gv100: initial support

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