Created attachment 115731 [details]
FHD Panel Datasheet.

Due this datasheet the panel looks the same as for DP configuration comparing
whith N133HSE-EA1 (asus u38n) panel. So it needs 2 lanes to init video stream.

As for your dmesg, I see problem in dp_aux_ch and training procedure (the
voltage and emphasis is 0 which is not right at this point). Need to debug
further when I publish my patch and if it not help.

One more thing, do you have FullHD (1920x1080) panel or WHD (1366x768) one.
Because on Lenovo site I see Thinkpad e455 base model with WHD. The last one
need only 1 DisplayPort lane to work.