drm/stm: Add STM32 LTDC driver

This controller provides output signals to interface directly a variety
of LCD and TFT panels. These output signals are: RGB signals
(up to 24bpp), vertical & horizontal synchronisations, data enable and
the pixel clock.

Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Yannick Fertre <yannick.fertre@st.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Link: http://patchwork.freedesktop.org/patch/msgid/1492164819-10513-5-git-send-email-yannick.fertre@st.com
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 78d7fc0..f57540d 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -246,6 +246,8 @@
 
 source "drivers/gpu/drm/tegra/Kconfig"
 
+source "drivers/gpu/drm/stm/Kconfig"
+
 source "drivers/gpu/drm/panel/Kconfig"
 
 source "drivers/gpu/drm/bridge/Kconfig"