[TCP] tcp-lp: bug fix for oops in 2.6.18-rc6

Sorry that the patch submited yesterday still contain a small bug.
This version have already been test for hours with BT connections. The
oops is now difficult to reproduce.

Signed-off-by: Wong Hoi Sing Edison <hswong3i@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>