Add RoboSwitch driver interface for wpa_supplicant

Find attached the patch that creates a new driver: roboswitch. This
driver adds support for wired authentication with a Broadcom
RoboSwitch chipset. For example it is now possible to do wired
authentication with a Linksys WRT54G router running OpenWRT.

LIMITATIONS
- At the moment the driver does not support the BCM5365 series (though
adding it requires just some register tweaks).
- The driver is also limited to Linux (this is a far more technical
restriction).
- In order to compile against a 2.4 series you need to edit
include/linux/mii.h and change all references to "u16" in "__u16". I
have submitted a patch upstream that will fix this in a future version
of the 2.4 kernel. [These modifications (and more) are now included in
the kernel source and can be found in versions 2.4.37-rc2 and up.]

USAGE
- Usage is similar to the wired driver. Choose the interfacename of
the vlan that contains your desired authentication port on the router.
This name must be formatted as <interface>.<vlan>, which is the
default on all systems I know.

wpa_supplicant/README

@@ -525,6 +525,7 @@ drivers:
   broadcom = Broadcom wl.o driver
   ipw = Intel ipw2100/2200 driver (old; use wext with Linux 2.6.13 or newer)
   wired = wpa_supplicant wired Ethernet driver
+  roboswitch = wpa_supplicant Broadcom switch driver
   bsd = BSD 802.11 support (Atheros, etc.)
   ndis = Windows NDIS driver
 
@@ -694,8 +695,8 @@ network={
 }
 
 
-6) Authentication for wired Ethernet. This can be used with 'wired' interface
-   (-Dwired on command line).
+6) Authentication for wired Ethernet. This can be used with 'wired' or
+   'roboswitch' interface (-Dwired or -Droboswitch on command line).
 
 ctrl_interface=/var/run/wpa_supplicant
 ctrl_interface_group=wheel