drm/exynos: add mode_fixup callback to exynos_drm_crtc_ops

crtc::mode_fixup callback is required by crtcs which internally use
a different mode than requested by user - case of Exynos Mixer.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Reviewed-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.h b/drivers/gpu/drm/exynos/exynos_drm_drv.h
index f8bae4cb..c6847fa 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_drv.h
+++ b/drivers/gpu/drm/exynos/exynos_drm_drv.h
@@ -136,6 +136,9 @@ struct exynos_drm_crtc_ops {
 	u32 (*get_vblank_counter)(struct exynos_drm_crtc *crtc);
 	enum drm_mode_status (*mode_valid)(struct exynos_drm_crtc *crtc,
 		const struct drm_display_mode *mode);
+	bool (*mode_fixup)(struct exynos_drm_crtc *crtc,
+			   const struct drm_display_mode *mode,
+			   struct drm_display_mode *adjusted_mode);
 	int (*atomic_check)(struct exynos_drm_crtc *crtc,
 			    struct drm_crtc_state *state);
 	void (*atomic_begin)(struct exynos_drm_crtc *crtc);