staging: gdm72xx: Add GCT GDM72xx WiMAX driver.

This patch provides the kernel driver for the GDM72xx WiMAX chips
developed by GCT Semiconductor, Inc., which enables mobile WiMAX
connection on the Linux host.

Signed-off-by: Sage Ahn <syahn@gctsemi.com>
Cc: Ben Chan <benchan@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>