video: Show an error when a vidconsole function fails

At present these functions fail silently even when debugging, which is not
very helpful. Add a way to print a message to the serial output when an
error is detected.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Anatolij Gustschin <agust@denx.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
1 file changed