drm/nouveau: fix allocation of notifier object

Commit 73412c38 ("drm/nouveau: allocate
kernel's notifier object at end of block") intended to align end of
notifier block to page boundary, but start of block was miscalculated
to be off by -16 bytes. Fix it.
Signed-off-by: NMarcin Slusarz <marcin.slusarz@gmail.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_dma.c

@@ -83,7 +83,7 @@ nouveau_dma_init(struct nouveau_channel *chan)
 		return ret;
 
 	/* NV_MEMORY_TO_MEMORY_FORMAT requires a notifier object */
-	ret = nouveau_notifier_alloc(chan, NvNotify0, 32, 0xfd0, 0x1000,
+	ret = nouveau_notifier_alloc(chan, NvNotify0, 32, 0xfe0, 0x1000,
 				     &chan->m2mf_ntfy);
 	if (ret)
 		return ret;