drm/nouveau/bus/gp104: initial support

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

drivers/gpu/drm/nouveau/nvkm/engine/device/base.c

@@ -2186,6 +2186,7 @@ nv134_chipset = {
 	.name = "GP104",
 	.bar = gf100_bar_new,
 	.bios = nvkm_bios_new,
+	.bus = gf100_bus_new,
 	.devinit = gm200_devinit_new,
 	.fb = gp104_fb_new,
 	.imem = nv50_instmem_new,