net/bootp.c: fix tftp load if autoload environment var isn't set

Commit 09349866 (Put common autoload code into auto_load() function)
broke handling of autoload environment variable not being set.
The bootp/dhcp code will just keep on requesting IP address forever
and never start TFTP download.

Fix it by moving TftpStart() outside the conditional like it was before.
Signed-off-by: NPeter Korsgaard <jacmet@sunsite.dk>
Tested-by: NFabio Estevam <fabio.estevam@freescale.com>
Acked-by: NSimon Glass <sjg@chromium.org>

net/bootp.c

@@ -164,8 +164,8 @@ static void auto_load(void)
 			return;
 		}
 #endif
-	TftpStart();
 	}
+	TftpStart();
 }
 
 #if !defined(CONFIG_CMD_DHCP)