General revision of RoboSwitch driver

General revision of RoboSwitch driver

Attached is a patch for the RoboSwitch driver in trunk. It is a
general revision of the source code.

Changes:
- Improved IEEE 802.1X conformance ([1])
- Better conformity to Broadcom specifications
- Fixed compatibility with different chipset revisions

It is worth noting that performance may drop a little using the new
driver. This can be overcome by using "multicast_only=1" as a
parameter. In that case only packets to the PAE group address are
regarded, as the previous revision of the driver did. A more detailed
description of the parameter and it's consequences is available at [2]
(summary: use "multicast_only=1" whenever possible).

[1] http://lists.shmoo.com/pipermail/hostap/2009-February/019398.html
[2] http://forum.openwrt.org/viewtopic.php?id=19873