wimax: basic API: kernel/user messaging, rfkill and reset

Implements the three basic operations provided by the stack's control
interface to WiMAX devices:

- Messaging channel between user space and driver/device

  This implements a direct communication channel between user space
  and the driver/device, by which free form messages can be sent back
  and forth.

  This is intended for device-specific features, vendor quirks, etc.

- RF-kill framework integration

  Provide most of the RF-Kill integration for WiMAX drivers so that
  all device drivers have to do is after wimax_dev_add() is call
  wimax_report_rfkill_{hw,sw}() to update initial state and then every
  time it changes.

  Provides wimax_rfkill() for the kernel to call to set software
  RF-Kill status and/or query current hardware and software switch
  status.

  Exports wimax_rfkill() over generic netlink to user space.

- Reset a WiMAX device

  Provides wimax_reset() for the kernel to reset a wimax device as
  needed and exports it over generic netlink to user space.

This API is clearly limited, as it still provides no way to do the
basic scan, connect and disconnect in a hardware independent way.  The
WiMAX case is more complex than WiFi due to the way networks are
discovered and provisioned.

The next developments are to add the basic operations so they can be
offerent by different drivers. However, we'd like to get more vendors
to jump in and provide feedback of how the user/kernel API/abstraction
layer should be.

The user space code for the i2400m, as of now, uses the messaging
channel, but that will change as the API evolves.

Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>