Staging: add rt2870 wireless driver

This is the Ralink RT2870 driver from the company that does horrible
things like reading a config file from /etc.  However, the driver that
is currently under development from the wireless development community
is not working at all yet, so distros and users are using this version
instead (quite common hardware on a lot of netbook machines).

So here is this driver, for now, until the wireless developers get a
"clean" version into the main tree, or until this version is cleaned up
sufficiently to move out of the staging tree.

Ported to the Linux build system and cleaned up a bit already by me.

Cc: Linux wireless <linux-wireless@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>