drm: Add support for ARM's HDLCD controller.

The HDLCD controller is a display controller that supports resolutions
up to 4096x4096 pixels. It is present on various development boards
produced by ARM Ltd and emulated by the latest Fast Models from the
company.

Cc: David Airlie <airlied@linux.ie>
Cc: Robin Murphy <robin.murphy@arm.com>

Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
[Kconfig cleanup and !CONFIG_PM fixes]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/arm/Kconfig

@@ -0,0 +1,27 @@
+config DRM_ARM
+	bool
+	help
+	  Choose this option to select drivers for ARM's devices
+
+config DRM_HDLCD
+	tristate "ARM HDLCD"
+	depends on DRM && OF && (ARM || ARM64)
+	depends on COMMON_CLK
+	select DRM_ARM
+	select DRM_KMS_HELPER
+	select DRM_KMS_FB_HELPER
+	select DRM_KMS_CMA_HELPER
+	help
+	  Choose this option if you have an ARM High Definition Colour LCD
+	  controller.
+
+	  If M is selected the module will be called hdlcd.
+
+config DRM_HDLCD_SHOW_UNDERRUN
+	bool "Show underrun conditions"
+	depends on DRM_HDLCD
+	default n
+	help
+	  Enable this option to show in red colour the pixels that the
+	  HDLCD device did not fetch from framebuffer due to underrun
+	  conditions.