Change initial connection timeouts again. Be more like BSD libstand version.

grub-core/net/tftp.c

@@ -37,7 +37,8 @@ GRUB_MOD_LICENSE ("GPLv3+");
  * XXX allow longer for initial connection since it might require spawning
  * a server instance.
  */
-#define TFTP_INITIAL_TIMO 2000
+#define TFTP_MIN_TIMO 2000
+#define TFTP_MAX_TIMO 20000
 
 /* IP port for the MTFTP server used for Intel's PXE */
 enum
@@ -408,7 +409,7 @@ tftp_open (struct grub_file *file, const char *filename)
 
   /* Receive OACK packet.  */
   nbd = nb.data;
-  for (i = 0; i < GRUB_NET_TRIES; i++)
+  for (i = TFTP_MIN_TIMO; i < TFTP_MAX_TIMO; i *= 2)
     {
       nb.data = nbd;
       err = grub_net_send_udp_packet (data->sock, &nb);
@@ -419,8 +420,7 @@ tftp_open (struct grub_file *file, const char *filename)
 	  grub_free (data);
 	  return err;
 	}
-      grub_net_poll_cards (TFTP_INITIAL_TIMO + (i * GRUB_NET_INTERVAL_ADDITION),
-                           &data->have_oack);
+      grub_net_poll_cards (i, &data->have_oack);
       if (data->have_oack)
 	break;
     }