tcp: /proc/net/tcp rto,ato values not scaled properly (v2)

I found another case where we are sending information to userspace
in the wrong HZ scale.  This should have been fixed back in 2.5 :-(

This means an ABI change but as it stands there is no way for an application
like ss to get the right value.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>