drm/nouveau: Use drm_crtc_vblank_crtc()

Replace the open coded drm_crtc_vblank_crtc() with the real
thing.

Cc: Karol Herbst <kherbst@redhat.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Danilo Krummrich <dakr@redhat.com>
Cc: nouveau@lists.freedesktop.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240408190611.24914-4-ville.syrjala@linux.intel.com


Reviewed-by: Lyude Paul <lyude@redhat.com>