uboot-imx

dm: video: Add a operation to display uclass

The current display class only allow to get timing from edid.
So add a operation to get timing directly from driver.
In driver, I will use fdtdec_decode_display_timing to get timing.

Signed-off-by: Jacob Chen <jacob-chen@iotwrt.com>
Acked-by: Simon Glass <sjg@chromium.org>