Staging: gdm72xx: Remove gdm72xx driver

Remove support for gdm72xx driver from the kernel since Wimax is dead.
[1] http://www.networkworld.com/article/2220370/4g/wimax-is-dead.html
[2] http://www.androidcentral.com/sprint-confirms-wimax-shutdown-november-6-2015



Chrome OS can distribute this driver alongside their library.

Signed-off-by: Shraddha Barke <shraddha.6596@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>