Remove account's PreferIPv6MediaTitle setting

app/src/main/kotlin/com/tutpro/baresip/Account.kt

@@ -20,7 +20,6 @@ class Account(val accp: String) {
     var videoCodec = ArrayList<String>()
     var regint = Api.account_regint(accp)
     var mediaEnc = Api.account_mediaenc(accp)
-    var preferIPv6Media = false
     var dtmfMode = Api.account_dtmfmode(accp)
     var answerMode = Api.account_answermode(accp)
     var vmUri = Api.account_vm_uri(accp)
@@ -56,9 +55,6 @@ class Account(val accp: String) {
         }
 
         val extra = Api.account_extra(accp)
-        preferIPv6Media = Utils.paramValue(extra,"prefer_ipv6_media") == "yes"
-        if (!preferIPv6Media)
-            preferIPv6Media = Api.account_mediaaf(accp) == Api.AF_INET6
         callHistory = Utils.paramValue(extra,"call_history") == ""
 
     }
@@ -108,8 +104,6 @@ class Account(val accp: String) {
 
         if (mediaEnc != "") res += ";mediaenc=${mediaEnc}"
 
-        if (preferIPv6Media) res += ";mediaaf=ipv6"
-
         res = if (vmUri == "")
             "$res;mwi=no"
         else