Resend a packet if we got the wrong buffer in status.

include/grub/net.h

@@ -139,6 +139,7 @@ struct grub_net_card
     {
       struct grub_efi_simple_network *efi_net;
       grub_efi_handle_t efi_handle;
+      grub_size_t last_pkt_size;
     };
 #endif
     void *data;