tun: remove copyright printing

Printing copyright does not give any useful information on the boot
process.
Furthermore, the email address printed is obsolete since
commit ba57b6f2 ("MAINTAINERS: fix bouncing tun/tap entries")

Signed-off-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>