EXAMPLE_SIMULATION is a new parameter introduced in Vivado 2013.4 to speed up simulation on the TX and also the RX side by bypassing the DRP-based reset sequence for GTH/GTP RX in simulation. This is to work around the requirement of UNISIM models for simulation, refer to (Xilinx Answer 53779) for GTH and (Xilinx Answer 53561) for GTP. This should be set to '1' only for simulation since the reset logic must be used when implementing the design for real hardware.
However, this parameter value is not passed correctly to the TX reset state machine; please make the following changes as a work-around. This will be fixed in the next version of the Wizard in Vivado Design Suite 2014.1.