Make rt73usb working configuring /etc/network/interfaces on Ubuntu/Debian

rt73usb wireless cards needs to be woke up before scanning so you have to add “pre-up ifconfig wlan0 up” in /etc/network/interfaces.

Example:

auto wlan0
iface wlan0 inet dhcp
pre-up ifconfig wlan0 up
wpa-ssid XYZ
wpa-psk XYZPRESHAREDKEY