drm/exynos: separate Mixer and HDMI drivers

Latest Exynos SoCs does not have Mixer IP, but they still have HDMI IP.
Their drivers should be configurable separately.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
diff --git a/drivers/gpu/drm/exynos/Kconfig b/drivers/gpu/drm/exynos/Kconfig
index bd1a415..1d7d9b8 100644
--- a/drivers/gpu/drm/exynos/Kconfig
+++ b/drivers/gpu/drm/exynos/Kconfig
@@ -62,9 +62,15 @@
 	help
 	  This enables support for DP device.
 
+config DRM_EXYNOS_MIXER
+	bool "Exynos DRM Mixer"
+	depends on DRM_EXYNOS && !VIDEO_SAMSUNG_S5P_TV
+	help
+	  Choose this option if you want to use Exynos Mixer for DRM.
+
 config DRM_EXYNOS_HDMI
 	bool "Exynos DRM HDMI"
-	depends on DRM_EXYNOS && !VIDEO_SAMSUNG_S5P_TV
+	depends on DRM_EXYNOS && !VIDEO_SAMSUNG_S5P_TV && (DRM_EXYNOS_MIXER || DRM_EXYNOS5433_DECON)
 	help
 	  Choose this option if you want to use Exynos HDMI for DRM.