drm/nouveau/fb/gk20a: use regular gf100's functions

gk20a's FB is not special compared to other Kepler chips, besides the
fact it does not have VRAM. Use the regular gf100 hooks instead of the
incomplete versions we rewrote.
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-By: Karol Herbst <karolherbst@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nvkm/subdev/fb/gk20a.c

 /*
- * Copyright (c) 2014, NVIDIA CORPORATION. All rights reserved.
+ * Copyright (c) 2014-2016, NVIDIA CORPORATION. All rights reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
@@ -22,21 +22,14 @@
 #include "priv.h"
 #include "gf100.h"
 
-#include <core/memory.h>
-
-static void
-gk20a_fb_init(struct nvkm_fb *fb)
-{
-	struct nvkm_device *device = fb->subdev.device;
-	nvkm_wr32(device, 0x100cc8, nvkm_memory_addr(fb->mmu_wr) >> 8);
-	nvkm_wr32(device, 0x100ccc, nvkm_memory_addr(fb->mmu_rd) >> 8);
-}
-
+/* GK20A's FB is similar to GF100's, but without the ability to allocate VRAM */
 static const struct nvkm_fb_func
 gk20a_fb = {
+	.dtor = gf100_fb_dtor,
 	.oneinit = gf100_fb_oneinit,
-	.init = gk20a_fb_init,
+	.init = gf100_fb_init,
 	.init_page = gf100_fb_init_page,
+	.intr = gf100_fb_intr,
 	.memtype_valid = gf100_fb_memtype_valid,
 };