update: tftp: dfu: Extend update_tftp() function to support DFU

This code allows using DFU defined mediums for storing data received via
TFTP protocol.

It reuses and preserves functionality of legacy code at common/update.c.

The update_tftp() function now accepts parameters - namely medium device
name and its number (e.g. mmc 1).

Without this information passed old behavior is preserved.

Signed-off-by: Lukasz Majewski <l.majewski@majess.pl>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

common/main.c

@@ -75,7 +75,7 @@ void main_loop(void)
 	run_preboot_environment_command();
 
 #if defined(CONFIG_UPDATE_TFTP)
-	update_tftp(0UL);
+	update_tftp(0UL, NULL, NULL);
 #endif /* CONFIG_UPDATE_TFTP */
 
 	s = bootdelay_process();