hostapd/RADIUS_server: add config option for IPv6

Even though IPv6 support for hostapd RADIUS server is implemented
(flag `-6`), it's not possible to enable it from configuration.

This commit adds this option and adapts init script.

Signed-off-by: Dávid Benko <davidbenko@davidbenko.dev>
Link: https://github.com/openwrt/openwrt/pull/18089
Signed-off-by: Robert Marko <robimarko@gmail.com>

package/network/services/hostapd/files/radius.config

@@ -1,5 +1,6 @@
 config radius
 	option disabled '1'
+	option ipv6 '1'
 	option ca_cert '/etc/radius/ca.pem'
 	option cert '/etc/radius/cert.pem'
 	option key '/etc/radius/key.pem'

package/network/services/hostapd/files/radius.init

@@ -12,6 +12,7 @@ radius_start() {
 
 	[ "$disabled" -gt 0 ] && return
 
+	config_get_bool ipv6 "$cfg" ipv6 1
 	config_get ca "$cfg" ca_cert
 	config_get key "$cfg" key
 	config_get cert "$cfg" cert
@@ -28,6 +29,7 @@ radius_start() {
 		-s "$clients" -u "$users" \
 		-p "$auth_port" -P "$acct_port" \
 		-i "$identity"
+	[ "$ipv6" -gt 0 ] && procd_append_param command -6
 	procd_close_instance
 }