console: rename do_vtxprintf to do_printk_va_list and use it

The name is more consistent with what we have elsewhere,
and the callsite didn't build at all (with vboot enabled)

Change-Id: I3576f3b8f737d360f68b67b6ce1683199948776d
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-on: http://review.coreboot.org/10096
Tested-by: build bot (Jenkins)

src/vendorcode/google/chromeos/vboot2/verstage.c

@@ -45,7 +45,7 @@ void vb2ex_printf(const char *func, const char *fmt, ...)
 
 	printk(BIOS_INFO, "VB2:%s() ", func);
 	va_start(args, fmt);
-	vprintk(BIOS_INFO, fmt, args);
+	do_printk_va_list(BIOS_INFO, fmt, args);
 	va_end(args);
 
 	return;