drbd: Fix for the connection problems on high latency links

It seems that the real cause of all the issues where that
we did not noticed in drbd_try_connect() when the other
guy closes one socket if the round trip time gets higher
than 100ms. There were that 100ms hard coded!

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>