ivy: Add a possiblity for mainboard early init.

This is needed for stout EC init.

Change-Id: I5c73499c17763229840152a473a2d820802ee2f6
Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-on: https://review.coreboot.org/13535
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

util/autoport/bd82x6x.go

@@ -358,6 +358,10 @@ void rcba_config(void)
 	guessedMap := GuessSPDMap(ctx)
 
 	sb.WriteString(`
+void mainboard_early_init(int s3resume)
+{
+}
+
 /* FIXME: Put proper SPD map here. */
 void mainboard_get_spd(spd_raw_data *spd)
 {