staging: wilc1000: remove use of unnecessary 'wilc_connected_ssid' variable
'wilc_connected_ssid' actually used to store the BSSID information for
connected BSSID. 'wilc_vif' already has 'bssid' variable to store the
same information. So refactor code to remove 'wilc_connected_ssid' and
instead used 'wilc_vif' struct 'bssid' element.