The usage menu shown when running the hidden "link get_sta" command is not
mentioning the need for the MAC address argument. Without this, the cmd is
always failing with the output shown below.
$ ./iw dev wlan0 link get_sta
Usage: ./iw [options] dev <devname> link get_sta
...
To avoid this, let the user know about the mandatory "MAC address" argument
like below.
$ ./iw dev wlan0 link get_sta
Usage: ./iw [options] dev <devname> link get_sta <mac-addr>
...