You can power both from one power supply, providing that power supply can provide enough current to run both. The cable you linked to, powers the Pi from the display board. Your power supply would be plugged into the micro USB on the display board. There are also Y cables out there. Your power supply plugs into it, then it splits to two cables, one plugs into the Pi and one to the display.
I made my own cables up. My display and Pi are both powered from a common power supply.