dm: x86: video: Add a driver-model driver for ivybridge graphics

At present we use the legacy vesa driver for graphics. Add a driver which
supports driver model. This can be probed only when needed, removing the
need to start up the display if it is not used.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>