IMS: Update carrier config for RTT API

Change-Id: Iabde7b0569b6ff0f306bd9db76a7adaabea9d7e0
CRs-Fixed: 2828959
diff --git a/ims/ims-ext-common/src/org/codeaurora/ims/utils/QtiImsExtUtils.java b/ims/ims-ext-common/src/org/codeaurora/ims/utils/QtiImsExtUtils.java
index 5eb7be1..97ecf9c 100644
--- a/ims/ims-ext-common/src/org/codeaurora/ims/utils/QtiImsExtUtils.java
+++ b/ims/ims-ext-common/src/org/codeaurora/ims/utils/QtiImsExtUtils.java
@@ -648,7 +648,7 @@
     // False otherwise
     public static boolean isRttMergeSupported(int phoneId, Context context) {
         return isCarrierConfigEnabled(phoneId, context,
-            CarrierConfigManager.KEY_ALLOW_MERGING_RTT_CALLS_BOOL);
+            "allow_merging_rtt_calls_bool");
     }
 
     // Returns true if Carrier supports Cancel Modify Call