Add new reason code for IMS Call ended during conference merge process

Test: Following scenarios for VoLTE and CS call and
      verified the cause sent in PreciseCallState.

 1) Conference call merge
 2) Conference call, one remote party ends the call
 3) Conference call, all remote parties end the call
 4) Conference call, hangup locally
 5) Normal call and hangup locally
 6) Normal call and remote party ends the call

Bug: 38225047
Change-Id: I36edb0cbff4b130b0942a46dc6c15a7d842789c2
diff --git a/telephony/java/com/android/ims/ImsReasonInfo.java b/telephony/java/com/android/ims/ImsReasonInfo.java
index bd8492b3..48f07d6 100644
--- a/telephony/java/com/android/ims/ImsReasonInfo.java
+++ b/telephony/java/com/android/ims/ImsReasonInfo.java
@@ -45,6 +45,8 @@
     public static final int CODE_LOCAL_IMS_SERVICE_DOWN = 106;
     // No pending incoming call exists
     public static final int CODE_LOCAL_NO_PENDING_CALL = 107;
+    // IMS Call ended during conference merge process
+    public static final int CODE_LOCAL_ENDED_BY_CONFERENCE_MERGE = 108;
 
     // IMS -> Telephony
     // Service unavailable; by power off