Make the BSSID and SSID fields optional when configuring a neighbor
report into hostapd.
Both options can now be an empty string. For the BSSID, the first 6 byte
are copied from the neighbor report. For the SSID, the SSID for the
affected hostapd BSS is used.
Signed-off-by: David Bauer <mail@david-bauer.net>