staging: brcm80211: store BSSID in driver config information

When mac80211 informs about new BSSID this was configured toward
the hardware device, but the information is also needed inside
the driver itself. This  patch takes care of that.

Reviewed-by: Roland Vossen <rvossen@broadcom.com>
Reviewed-by: Brett Rudley <brudley@broadcom.com>
Reviewed-by: Henry Ptasinski <henryp@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>