bpf: netdev is never null in __dev_map_flush

No need to test for it in fast-path, every dev in bpf_dtab_netdev
is guaranteed to be non-NULL, otherwise dev_map_update_elem() will
fail in the first place.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

kernel/bpf/devmap.c

@@ -226,12 +226,10 @@ void __dev_map_flush(struct bpf_map *map)
 		if (unlikely(!dev))
 			continue;
 
-		netdev = dev->dev;
 		__clear_bit(bit, bitmap);
-		if (unlikely(!netdev || !netdev->netdev_ops->ndo_xdp_flush))
-			continue;
-
-		netdev->netdev_ops->ndo_xdp_flush(netdev);
+		netdev = dev->dev;
+		if (likely(netdev->netdev_ops->ndo_xdp_flush))
+			netdev->netdev_ops->ndo_xdp_flush(netdev);
 	}
 }