settings: allow enabling ethernet tethering independent of link state

A user should be able to enable tethering even if the interface does not
have link yet. Therefore, the toggle should be active if any interface
is available, independent of its link state.

Test: TH
Bug: 234036868
Change-Id: I2ae25207a766d71217dd6d17f3f9b74ceb261238

src/com/android/settings/network/EthernetTetherPreferenceController.java

@@ -50,7 +50,7 @@ public final class EthernetTetherPreferenceController extends TetherBasePreferen
     @OnLifecycleEvent(Lifecycle.Event.ON_START)
     public void onStart() {
         mEthernetListener = (iface, state, role, configuration) -> {
-            if (state == EthernetManager.STATE_LINK_UP) {
+            if (state != EthernetManager.STATE_ABSENT) {
                 mAvailableInterfaces.add(iface);
             } else {
                 mAvailableInterfaces.remove(iface);