Don't check carrierconfig for displaying RTT setting

The RTT setting will be reused by Dialer even if the ignore-rtt-setting
carrier config is on, so don't hide it when the carrier config is set.

Change-Id: I547883cfbb9aeb793fad0cad98cee434fa07472e
Fix: 140203147
Test: manual
diff --git a/src/com/android/phone/settings/AccessibilitySettingsFragment.java b/src/com/android/phone/settings/AccessibilitySettingsFragment.java
index b074f20..7c487b2 100644
--- a/src/com/android/phone/settings/AccessibilitySettingsFragment.java
+++ b/src/com/android/phone/settings/AccessibilitySettingsFragment.java
@@ -199,20 +199,11 @@
     }
 
     private boolean shouldShowRttSetting() {
-        CarrierConfigManager configManager =
-                (CarrierConfigManager) mContext.getSystemService(Context.CARRIER_CONFIG_SERVICE);
         // Go through all the subs -- if we want to display the RTT setting for any of them, do
         // display it.
         for (int subId : SubscriptionController.getInstance().getActiveSubIdList(true)) {
-            // In order to display the setting, we want:
-            // 1. The subscription supports RTT
-            // 2. The subscription isn't configured by the carrier to have the setting always-on
-            //    (see the documentation for the carrier config key)
             if (PhoneGlobals.getInstance().phoneMgr.isRttSupported(subId)) {
-                if (!configManager.getConfigForSubId(subId).getBoolean(
-                        CarrierConfigManager.KEY_IGNORE_RTT_MODE_SETTING_BOOL, false)) {
-                    return true;
-                }
+                return true;
             }
         }
         return false;