drm/nvc0/fifo: fix typos in unload_context

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
diff --git a/drivers/gpu/drm/nouveau/nvc0_fifo.c b/drivers/gpu/drm/nouveau/nvc0_fifo.c
index fb4f594..6f9f341 100644
--- a/drivers/gpu/drm/nouveau/nvc0_fifo.c
+++ b/drivers/gpu/drm/nouveau/nvc0_fifo.c
@@ -210,10 +210,10 @@
 	int i;
 
 	for (i = 0; i < 128; i++) {
-		if (!(nv_rd32(dev, 0x003004 + (i * 4)) & 1))
+		if (!(nv_rd32(dev, 0x003004 + (i * 8)) & 1))
 			continue;
 
-		nv_mask(dev, 0x003004 + (i * 4), 0x00000001, 0x00000000);
+		nv_mask(dev, 0x003004 + (i * 8), 0x00000001, 0x00000000);
 		nv_wr32(dev, 0x002634, i);
 		if (!nv_wait(dev, 0x002634, 0xffffffff, i)) {
 			NV_INFO(dev, "PFIFO: kick ch %d failed: 0x%08x\n",