Staging: rt2870sta interface names

The rest of the known universe prefers wlanN for wireless interface names, to
the point that some distro configuration tools, such as opensuse's Yast, don't
even allow the user to enter a name, and simply pre-select "wlan".

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>