rt2x00: Fix hw crypto in AP mode for some devices

The BSSID register shouldn't be set in AP mode on some older devices (like
rt73usb) as it breaks hw crypto on these. However, rt2800 devices explicitly
need the BSSID register set to the same value as our own MAC address (only
in AP mode).

Hence, don't set the BSSID from rt2x00lib but move it down into rt2800 to
avoid problems on older devices.

This fixes a regression (at least for rt73usb) and avoids a new regression
for rt2800 devices in 2.6.36.

Reported-by: Johannes Stezenbach <js@sig21.net>
Reported-by: Lee <lee-in-berlin@web.de>
Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>