Do not update state of Disconnected Connection

Add a check in TelephonyConnection#updateStateInternal to make sure that
its Connection is not null before trying to update its state. This can
happen when reseting the Connection state override for an outgoing CDMA
call.

Bug: 27250284
Change-Id: Iff765977b5b57d6cb6d52d70e5780a2215318fc3
diff --git a/src/com/android/services/telephony/TelephonyConnection.java b/src/com/android/services/telephony/TelephonyConnection.java
index 6ab1f6b..8f6c57e 100644
--- a/src/com/android/services/telephony/TelephonyConnection.java
+++ b/src/com/android/services/telephony/TelephonyConnection.java
@@ -940,6 +940,9 @@
     }
 
     void updateStateInternal() {
+        if (mOriginalConnection == null) {
+            return;
+        }
         Call.State newState;
         // If the state is overridden and the state of the original connection hasn't changed since,
         // then we continue in the overridden state, else we go to the original connection's state.