netdevsim: move sdev specific bpf debugfs files to sdev dir

Some netdevsim bpf debugfs files are per-sdev, yet they are defined per
netdevsim instance. Move them under sdev directory.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>