dm: video: Add support for video bridges

A video bridge typically converts video from one format to another, e.g.
DisplayPort to LVDS. Add driver model support for these with a simple
interface to control activation and backlight. The uclass supports GPIO
control of power and reset lines.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index 9ae23e8..3244cd7 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -240,3 +240,5 @@
 	   HDMI. At present only eDP is supported by U-Boot. This option
 	   enables this support which can be used on devices which
 	   have an eDP display connected.
+
+source "drivers/video/bridge/Kconfig"