atm: [iphase] 64-bit cleanup

This fixes the most obvious 64-bit problems, but it is still very very
broken in other aspects.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Chas Williams <chas@cmf.nrl.navy.mil>
Signed-off-by: David S. Miller <davem@davemloft.net>