CustomSliceable.getBroadcastIntent should use FLAG_MUTABLE

Bug: 173597689
Test: build pass and manual test for wifi slice
Change-Id: I16ebdaa591ee3e072ab46cd3efdd5e22edc88b46

src/com/android/settings/slices/CustomSliceable.java

@@ -95,7 +95,7 @@ public interface CustomSliceable extends Sliceable {
                 .setData(getUri())
                 .setClass(context, SliceBroadcastReceiver.class);
         return PendingIntent.getBroadcast(context, 0 /* requestCode */, intent,
-                PendingIntent.FLAG_UPDATE_CURRENT | PendingIntent.FLAG_IMMUTABLE);
+                PendingIntent.FLAG_UPDATE_CURRENT | PendingIntent.FLAG_MUTABLE);
     }
 
     @Override
@@ -119,4 +119,4 @@ public interface CustomSliceable extends Sliceable {
                     "Invalid sliceable class: " + sliceable, e);
         }
     }
-}
+}