video: console: Fix default font selection

Some callers expect to call this with NULL font name to select the
default font (eg. boot/scene.c). Without handling the NULL condition
U-Boot crashes instead of displaying a bootflow GUI menu.

Signed-off-by: Ondrej Jirman <megi@xff.cz>
Cc: Anatolij Gustschin <agust@denx.de>
diff --git a/drivers/video/console_core.c b/drivers/video/console_core.c
index 1f93b1b..b5d0e3d 100644
--- a/drivers/video/console_core.c
+++ b/drivers/video/console_core.c
@@ -201,6 +201,12 @@
 {
 	struct video_fontdata *font;
 
+	if (!name) {
+		if (fonts->name)
+			console_set_font(dev, fonts);
+		return 0;
+	}
+
 	for (font = fonts; font->name; font++) {
 		if (!strcmp(name, font->name)) {
 			console_set_font(dev, font);