afs: do not send list of client addresses

David Howells says:
  I'm told that there's not really any point populating the list.
  Current OpenAFS ignores it, as does AuriStor - and IBM AFS 3.6 will
  do the right thing.
  The list is actually useless as it's the client's view of the world,
  not the servers, so if there's any NAT in the way its contents are
  invalid.  Further, it doesn't support IPv6 addresses.

  On that basis, feel free to make it an empty list and remove all the
  interface enumeration.

V1 of this patch reworked the function to use a new helper for the
ifa_list iteration to avoid sparse warnings once the proper __rcu
annotations get added in struct in_device later.

But, in light of the above, just remove afs_get_ipv4_interfaces.

Compile tested only.

Cc: David Howells <dhowells@redhat.com>
Cc: linux-afs@lists.infradead.org
Signed-off-by: Florian Westphal <fw@strlen.de>
Tested-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>