mac80211: add support for specifying a per-device scan list

This is useful to bring up multiple client mode interfaces on a single
channel much faster without having to scan through a lot of channels

Signed-off-by: Felix Fietkau <nbd@nbd.name>

package/kernel/mac80211/files/lib/netifd/wireless/mac80211.sh

@@ -34,6 +34,7 @@ drv_mac80211_init_device_config() {
 	config_add_boolean noscan ht_coex acs_exclude_dfs
 	config_add_array ht_capab
 	config_add_array channels
+	config_add_array scan_list
 	config_add_boolean \
 		rxldpc \
 		short_gi_80 \
@@ -897,6 +898,7 @@ drv_mac80211_setup() {
 		rxantenna txantenna \
 		frag rts beacon_int:100 htmode
 	json_get_values basic_rate_list basic_rate
+	json_get_values scan_list scan_list
 	json_select ..
 
 	find_phy || {

package/network/services/hostapd/files/hostapd.sh

@@ -896,6 +896,7 @@ wpa_supplicant_prepare_interface() {
 	fi
 	wpa_supplicant_teardown_interface "$ifname"
 	cat > "$_config" <<EOF
+${scan_list:+freq_list=$scan_list}
 $ap_scan
 $country_str
 EOF