ethernet: remove IpClient null check before restart

aosp/2388903 added a null check for IpClient directly inside restart(),
so this null check can be removed.

Bug: 269387860
Test: TH
Change-Id: I68943651967047674b4084c6397e58abf1bb2110
diff --git a/service-t/src/com/android/server/ethernet/EthernetNetworkFactory.java b/service-t/src/com/android/server/ethernet/EthernetNetworkFactory.java
index 60485f1..bd138f9 100644
--- a/service-t/src/com/android/server/ethernet/EthernetNetworkFactory.java
+++ b/service-t/src/com/android/server/ethernet/EthernetNetworkFactory.java
@@ -469,9 +469,7 @@
             // TODO: Update this logic to only do a restart if required. Although a restart may
             //  be required due to the capabilities or ipConfiguration values, not all
             //  capabilities changes require a restart.
-            if (mIpClient != null) {
-                restart();
-            }
+            restart();
         }
 
         boolean isRestricted() {