drm/nouveau: Keep RAMIN heap within the channel.

The entire RAMIN is allocated to be 'size', but the heap is
specified as 'base' + 'size' inside RAMIN, so it will overflow
past RAMIN by 'base' bytes on NV50+ and clobber other allocatons
unless it's size is adjusted.
Signed-off-by: Younes Manton <younes.m@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_object.c

@@ -680,7 +680,7 @@ nouveau_gpuobj_channel_init_pramin(struct nouveau_channel *chan)
 		return ret;
 	}
 
-	ret = drm_mm_init(&chan->ramin_heap, base, size);
+	ret = drm_mm_init(&chan->ramin_heap, base, size - base);
 	if (ret) {
 		NV_ERROR(dev, "Error creating PRAMIN heap: %d\n", ret);
 		nouveau_gpuobj_ref(NULL, &chan->ramin);