fix nogo errors from checker SA4006

PiperOrigin-RevId: 443448448

pkg/sentry/fsimpl/tmpfs/benchmark_test.go

@@ -230,7 +230,6 @@ func BenchmarkVFS2TmpfsStat(b *testing.B) {
 				Mode:  0644,
 			})
 			vd.DecRef(ctx)
-			vd = vfs.VirtualDentry{}
 			if err != nil {
 				b.Fatalf("failed to create file %q: %v", filename, err)
 			}

pkg/tcpip/network/ipv4/ipv4_test.go

@@ -2756,7 +2756,7 @@ func TestReceiveFragments(t *testing.T) {
 
 				// Check IPv4 header in packet delivered by raw endpoint.
 				buf.Reset()
-				result, err = epRaw.Read(&buf, tcpip.ReadOptions{})
+				_, err = epRaw.Read(&buf, tcpip.ReadOptions{})
 				if err != nil {
 					t.Fatalf("(i=%d) epRaw.Read: %s", i, err)
 				}