ethernet_interface: Fix updates without interface idx

This fixes VLAN creation

Change-Id: I1d2fa8f9d20edfc49077f77d38e3ddcfbf49a6de
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/src/network_manager.cpp b/src/network_manager.cpp
index 014d0b4..2d0f506 100644
--- a/src/network_manager.cpp
+++ b/src/network_manager.cpp
@@ -133,6 +133,15 @@
             return;
         }
     }
+    else if (info.intf.name)
+    {
+        auto it = interfaces.find(*info.intf.name);
+        if (it != interfaces.end())
+        {
+            it->second->updateInfo(info.intf);
+            return;
+        }
+    }
     if (!info.intf.name)
     {
         auto msg = fmt::format("Can't create interface without name: {}",