video: Update truetype console to support copy buffer

Update the implementation to keep a track of what it changes in the frame
buffer and then tell the copy buffer about it. Use the special
vidconsole_memmove() helper so that memmove() operations are also
reflected in the copy buffer.

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