drm/nouveau: use correct conflicting framebuffer API

nouveau was calling the fbdev API which has issues with modules
and built-ins. Call the correct API.
Reported-by: NRandy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Fixes: 2dd4d163 ("drm/nouveau: remove open-coded version of remove_conflicting_pci_framebuffers()")
Link: https://lore.kernel.org/lkml/21b52c28-3ace-cd13-d8ce-f38f2c6b2a96@infradead.org/T/#uSigned-off-by: NDave Airlie <airlied@redhat.com>

drivers/gpu/drm/nouveau/nouveau_drm.c

@@ -697,7 +697,7 @@ static int nouveau_drm_probe(struct pci_dev *pdev,
 	nvkm_device_del(&device);
 
 	/* Remove conflicting drivers (vesafb, efifb etc). */
-	ret = remove_conflicting_pci_framebuffers(pdev, "nouveaufb");
+	ret = drm_fb_helper_remove_conflicting_pci_framebuffers(pdev, "nouveaufb");
 	if (ret)
 		return ret;