CAN: Use inode instead of kernel address for /proc file

Since the socket address is just being used as a unique identifier, its
inode number is an alternative that does not leak potentially sensitive
information.

CC-ing stable because MITRE has assigned CVE-2010-4565 to the issue.

Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: David S. Miller <davem@davemloft.net>