gianfar: incorrect TCP checksum when timestamps are enabled

Greetings.=0A=0AI'm working on MPC8548 based board (I started with 2.6.37-r=
c7, now upgraded=0Ato post release 2.6.37 git head).=0A=0AIt so appears, th=
at when tcp timestamps are enabled (default setting)=0ATCP checksums of out=
going SYN packets are calculated incorrectly. This=0Acauses remote machines=
 to reject such packets, effectively preventing any=0Auseful network use. T=
he problem is reproducible every time.=0A=0AOther protocols appear to work =
reliably (UDP/DHCP do work).=0A=0AIf tcp timestamps are disabled, checksums=
 are calculated correctly.=0A=0ANetdev guys tend to think that the problem =
is with hardware checksum=0Aoffloading, the theory I'm going to test now.=
=0A=0A=0A=0A