Add required flag to registerReceiver call in TelephonyConnectionService

Android T adds support to allow a runtime receiver to be registered as
not exported, but to ensure apps can take advantage of this, calls to
registerReceiver must specify a flag indicating whether the receiver
should be exported for apps targeting T+ that are registering for
non-system broadcasts. This commit adds the RECEIVER_EXPORTED
flag to the receiver in TelephonyConnectionService since this
broadcast is protected by a privileged|role permission and is
expected from the Dialer.

Bug: 161145287
Test: Build
Change-Id: I2a98fb8b5c2326c7fb35a90d63aa081287340195
diff --git a/src/com/android/services/telephony/TelephonyConnectionService.java b/src/com/android/services/telephony/TelephonyConnectionService.java
index b6f785c..071376d 100644
--- a/src/com/android/services/telephony/TelephonyConnectionService.java
+++ b/src/com/android/services/telephony/TelephonyConnectionService.java
@@ -500,7 +500,7 @@
         IntentFilter intentFilter = new IntentFilter(
                 TelecomManager.ACTION_TTY_PREFERRED_MODE_CHANGED);
         registerReceiver(mTtyBroadcastReceiver, intentFilter,
-                android.Manifest.permission.MODIFY_PHONE_STATE, null);
+                android.Manifest.permission.MODIFY_PHONE_STATE, null, Context.RECEIVER_EXPORTED);
     }
 
     @Override