Add new driver 'rndis_wlan' for wireless RNDIS devices.

New driver for wireless RNDIS devices. So far only known chip that uses
wireless RNDIS is Broadcom 4320. Driver detects all RNDIS devices that
have RNDIS wireless physical medium. At least following devices are
detected:

  Buffalo WLI-U2-KG125S
  U.S. Robotics USR5421
  Belkin F5D7051
  Linksys WUSB54GSv2
  Linksys WUSB54GSC
  Asus WL169gE
  Eminent EM4045
  BT Voyager 1055
  Linksys WUSB54GSv1
  U.S. Robotics USR5420
  BUFFALO WLI-USB-G54

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>