This won't show on a per AP basis, but you can try the following commands to see all users connected to ports on APs/RAPs.
- show user | include 0/1 ( This should show users connected to port 1 of an AP/RAP. You can also use 0/2, 0/3, 0/4 for the other ports on a RAP-5.)
- show user | include Wired (must be capital W; depening on your environment, this may or may not produce the best results)
I suppose if you know the AP-Name, you can just run the following. it will also show you wireless users, but you can look for the Wired state column for the wired users.
- show user | include AP-NAME (actual name and capitalization)
I don't believe AOS supports multiple | commands like Cisco; otherwise you could run show user include the AP name and Wired.
As Mike suggested, if you have AirWave, you can also find this information.