Fix output switch will show empty slice

Use MediaDevice in the list to add row instead of use connectedDevice.
Becauae connectedDevice that got from getCurrentConnectedMediaDevice()
could be null.

Bug: 157611605
Test: make -j42 RunSettingsRoboTests
Change-Id: Ib51e3e436e65a9aaa5a35488191b8b2ad9cb6a4b

src/com/android/settings/media/MediaOutputSlice.java

@@ -106,7 +106,9 @@ public class MediaOutputSlice implements CustomSliceable {
             final MediaDevice connectedDevice = worker.getCurrentConnectedMediaDevice();
             if (devices.size() == 1) {
                 // Zero state
-                addRow(connectedDevice, connectedDevice, listBuilder);
+                for (MediaDevice device : devices) {
+                    addRow(device, device, listBuilder);
+                }
                 listBuilder.addRow(getPairNewRow());
             } else {
                 final boolean isTouched = worker.getIsTouched();