drm/nv20/fb: split implementation into nv20/nv25 pieces

There's more stuff that can be shared in the constructor, will be merged
together again later.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
diff --git a/drivers/gpu/drm/nouveau/Makefile b/drivers/gpu/drm/nouveau/Makefile
index a990df4..b80092b 100644
--- a/drivers/gpu/drm/nouveau/Makefile
+++ b/drivers/gpu/drm/nouveau/Makefile
@@ -65,6 +65,7 @@
 nouveau-y += core/subdev/fb/nv04.o
 nouveau-y += core/subdev/fb/nv10.o
 nouveau-y += core/subdev/fb/nv20.o
+nouveau-y += core/subdev/fb/nv25.o
 nouveau-y += core/subdev/fb/nv30.o
 nouveau-y += core/subdev/fb/nv40.o
 nouveau-y += core/subdev/fb/nv50.o