can: Fix raw_getname() leak

raw_getname() can leak 10 bytes of kernel memory to user

(two bytes hole between can_family and can_ifindex,
8 bytes at the end of sockaddr_can structure)

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Oliver Hartkopp <oliver@hartkopp.net>
Signed-off-by: David S. Miller <davem@davemloft.net>