b43/legacy: remove SSID code

The SSID programmed into the device is used by the ucode only
to reply to probe requests, a functionality we disable anyway
because it doesn't fit with the mac80211/hostapd programming
model. Therefore, it isn't useful to program the SSID into
device.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>