1. Fixed a issue in Ip4Config.c

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11615 6f19259b-4bc3-4df7-8a09-765794883524

MdeModulePkg/Universal/Network/Ip4ConfigDxe/Ip4Config.c

@@ -129,6 +129,9 @@ EfiNicIp4ConfigSetInfo (
     DispatchDpc ();
   }
 
+  if (NicConfig == NULL) {
+    return Status;
+  }
   //
   // A dedicated timer is used to poll underlying media status.In case of
   // cable swap, a new round auto configuration will be initiated. The timer