Add disallow_aps parameter to disallow BSSIDs/SSIDs

Add disallow_aps parameter to disallow BSSIDs/SSIDs

External programs can use this new parameter to prevent wpa_supplicant
from connecting to a list of BSSIDs and/or SSIDs. The disallowed BSSes
will still be visible in scan results and it is possible to run ANQP
operations with them, but BSS selection for connection will skip any
BSS that matches an entry in the disallowed list.

The new parameter can be set with the control interface SET command
using following syntax:

SET disallow_aps <disallow_list>
disallow_list ::= <ssid_spec> | <bssid_spec> | <disallow_list> | “”
SSID_SPEC ::= ssid <SSID_HEX>
BSSID_SPEC ::= bssid <BSSID_HEX>

For example:
wpa_cli set disallow_list "ssid 74657374 bssid 001122334455 ssid 68656c6c6f"
wpa_cli set disallow_list
(the empty value removes all entries)

Signed-hostap: Jouni Malinen <jouni@qca.qualcomm.com>