drm/nouveau/nvif: simplify and tidy library interfaces

A variety of tweaks to the NVIF library interfaces, mostly ripping out
things that turned out to be not so useful.

- Removed refcounting from nvif_object, callers are expected to not be
  stupid instead.
- nvif_client is directly reachable from anything derived from nvif_object,
  removing the need for heuristics to locate it
- _new() versions of interfaces, that allocate memory for the object
  they construct, have been removed.  The vast majority of callers used
  the embedded _init() interfaces.
- No longer storing constructor arguments (and the data returned from
  nvkm) inside nvif_object, it's more or less unused and just wastes
  memory.

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

drivers/gpu/drm/nouveau/nv50_fence.c

@@ -51,7 +51,7 @@ nv50_fence_context_new(struct nouveau_channel *chan)
 	fctx->base.read = nv10_fence_read;
 	fctx->base.sync = nv17_fence_sync;
 
-	ret = nvif_object_init(chan->object, NULL, NvSema, NV_DMA_IN_MEMORY,
+	ret = nvif_object_init(&chan->user, NvSema, NV_DMA_IN_MEMORY,
 			       &(struct nv_dma_v0) {
 					.target = NV_DMA_V0_TARGET_VRAM,
 					.access = NV_DMA_V0_ACCESS_RDWR,
@@ -66,7 +66,7 @@ nv50_fence_context_new(struct nouveau_channel *chan)
 		u32 start = bo->bo.mem.start * PAGE_SIZE;
 		u32 limit = start + bo->bo.mem.size - 1;
 
-		ret = nvif_object_init(chan->object, NULL, NvEvoSema0 + i,
+		ret = nvif_object_init(&chan->user, NvEvoSema0 + i,
 				       NV_DMA_IN_MEMORY, &(struct nv_dma_v0) {
 						.target = NV_DMA_V0_TARGET_VRAM,
 						.access = NV_DMA_V0_ACCESS_RDWR,