drm/nouveau: replace nv04_graph_fifo_access() use with direct reg bashing

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

diff --cc drivers/gpu/drm/nouveau/nouveau_drv.h
Simple merge

diff --cc drivers/gpu/drm/nouveau/nv04_graph.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/nv10_graph.c
Simple merge

diff --cc drivers/gpu/drm/nouveau/nv20_graph.c
Simple merge