staging: brcm80211: remove brcm80211 driver from the staging tree

With the mainline patch being applied to the wireless-next repository
by John Linville this driver is no longer needed under the staging
directory. This patch ends its life under the staging tree.

Cc: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>