staging: brcm80211: cleaned up TODO file

Brought TODO file in line with current driver state. Moved longer
term TODO items (the ones to be done once this driver
hits mainline) to website. Removed the bugs that have been solved.
Added new TODO items.

Signed-off-by: Roland Vossen <rvossen@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>