dm: video: Repurpose the 'displayport' uclass to 'display'

The current DisplayPort uclass is too specific. The operations it provides
are shared with other types of output devices, such as HDMI and LVDS LCD
displays.

Generalise the uclass so that it can be used with these devices as well.
Adjust the uclass to handle the EDID reading and conversion to
display_timing internally.

Also update nyan-big which is affected by this.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index ae122da..9ecfeae 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -293,12 +293,15 @@
 	option takes a string in the format understood by 'name_to_gpio'
 	function, e.g. PH1 for pin 1 of port H.
 
-config DISPLAY_PORT
-	bool "Enable DisplayPort support"
+config DISPLAY
+	bool "Enable Display support"
+	depends on DM
+	default y
 	help
-	   eDP (Embedded DisplayPort) is a standard widely used in laptops
-	   to drive LCD panels. This framework provides support for enabling
-	   these displays where supported by the video hardware.
+	   This supports drivers that provide a display, such as eDP (Embedded
+	   DisplayPort) and HDMI (High Definition Multimedia Interface).
+	   The devices provide a simple interface to start up the display,
+	   read display information and enable it.
 
 config VIDEO_SANDBOX_SDL
 	bool "Enable sandbox video console using SDL"