scsi_netlink: Remove dead and buggy code

The scsi netlink code confuses the netlink port id with a process id,
going so far as to read NETLINK_CREDS(skb)->pid instead of the correct
NETLINK_CB(skb).pid.  Fortunately it does not matter because nothing
registers to respond to scsi netlink requests.

The only interesting use of the scsi_netlink interface is
fc_host_post_vendor_event which sends a netlink multicast message.

Since nothing registers to handle scsi netlink messages kill all of the
registration logic, while retaining the same error handling behavior
preserving the userspace visible behavior and removing all of the
confused code that thought a netlink port id was a process id.

This was tested with a kernel allyesconfig build which had no problems.

Cc: James Bottomley <James.Bottomley@parallels.com>
Cc: James Smart <James.Smart@Emulex.Com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>