Missed one file in last commit

arch/z80/src/common/up_initialize.c

@@ -44,6 +44,7 @@
 #include <nuttx/arch.h>
 #include <nuttx/board.h>
 #include <nuttx/fs/fs.h>
+#include <nuttx/net/loopback.h>
 
 #include <arch/board/board.h>
 
@@ -181,5 +182,11 @@ void up_initialize(void)
   up_netinitialize();
 #endif
 
+#ifdef CONFIG_NETDEV_LOOPBACK
+  /* Initialize the local loopback device */
+
+  (void)localhost_initialize();
+#endif
+
   board_led_on(LED_IRQSENABLED);
 }