serial: make local functions static

Signed-off-by: Jeroen Hofstee <jeroen@myspectrum.nl>
diff --git a/drivers/video/cfb_console.c b/drivers/video/cfb_console.c
index 8567231..6aa50cb 100644
--- a/drivers/video/cfb_console.c
+++ b/drivers/video/cfb_console.c
@@ -944,7 +944,7 @@
 		CURSOR_SET;
 }
 
-void video_putc(struct stdio_dev *dev, const char c)
+static void video_putc(struct stdio_dev *dev, const char c)
 {
 #ifdef CONFIG_CFB_CONSOLE_ANSI
 	int i;
@@ -1158,7 +1158,7 @@
 		flush_cache(VIDEO_FB_ADRS, VIDEO_SIZE);
 }
 
-void video_puts(struct stdio_dev *dev, const char *s)
+static void video_puts(struct stdio_dev *dev, const char *s)
 {
 	int count = strlen(s);