console: unify printing current devices

Create stdio_print_current_devices() for this purpose

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/include/stdio_dev.h b/include/stdio_dev.h
index 8b06ccf..83da4cd 100644
--- a/include/stdio_dev.h
+++ b/include/stdio_dev.h
@@ -91,6 +91,7 @@
  */
 int	stdio_register (struct stdio_dev * dev);
 int	stdio_init (void);
+void	stdio_print_current_devices(void);
 #ifdef CONFIG_SYS_STDIO_DEREGISTER
 int	stdio_deregister(char *devname);
 #endif