video: console: Fix buffer overflow in cmd 'font list'

vidconsole_ops.get_font is documented to return -ENOENT after the last
video_fontdata entry.

Signed-off-by: Janne Grunau <j@jannau.net>
diff --git a/drivers/video/console_core.c b/drivers/video/console_core.c
index d17764d..9393636 100644
--- a/drivers/video/console_core.c
+++ b/drivers/video/console_core.c
@@ -225,7 +225,7 @@
 {
 	info->name = fonts[seq].name;
 
-	return 0;
+	return info->name ? 0 : -ENOENT;
 }
 
 int console_simple_select_font(struct udevice *dev, const char *name, uint size)