drm/nouveau/mmu/gp10b: use correct implementation

Reported-by: Mikko Perttunen <cyndis@kapsi.fi>
Fixes: 6359c98224 ("drm/nouveau/mmu/gp10b: fork from gf100")
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Tested-by: Thierry Reding <treding@nvidia.com>

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

@@ -2369,7 +2369,7 @@ nv13b_chipset = {
 	.imem = gk20a_instmem_new,
 	.ltc = gp100_ltc_new,
 	.mc = gp10b_mc_new,
-	.mmu = gf100_mmu_new,
+	.mmu = gp10b_mmu_new,
 	.secboot = gp10b_secboot_new,
 	.pmu = gm20b_pmu_new,
 	.timer = gk20a_timer_new,