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/Makefile b/drivers/video/Makefile
index 2ead7f1..599fe83 100644
--- a/drivers/video/Makefile
+++ b/drivers/video/Makefile
@@ -54,3 +54,5 @@
 obj-$(CONFIG_VIDEO_PARADE) += parade.o
 
 obj-${CONFIG_VIDEO_TEGRA124} += tegra124/
+
+obj-y += bridge/