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/bridge/Kconfig b/drivers/video/bridge/Kconfig
new file mode 100644
index 0000000..7ba6b17
--- /dev/null
+++ b/drivers/video/bridge/Kconfig
@@ -0,0 +1,8 @@
+config VIDEO_BRIDGE
+	bool "Support video bridges"
+	depends on DM
+	help
+	  Some platforms use video bridges to convert from one output to
+	  another. For example, where the SoC only supports eDP and the LCD
+	  requires LVDS, an eDP->LVDS bridge chip can be used to provide the
+	  necessary conversion. This option enables support for these devices.