wifi,mozilla: Fix maximum SSID length handling

An SSID can be 32 characters but the MAX_SSID_LEN macro is to declare the size of the buffers including the nul byte. This causes excessive variant_to_string: assertion 'len < max_len' failed errors if you happen to have a network with a full 32 character SSID. This can often occur for APs that advertise a hidden SSID by setting it to all zeros.

Fixes: #135 (closed)