drm/meson: venc: make drm_display_mode const

Before switching to bridge funcs, make sure drm_display_mode is passed
as const to the venc functions.
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jernej Škrabec <jernej.skrabec@siol.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20200304104052.17196-7-narmstrong@baylibre.com

drivers/gpu/drm/meson/meson_venc.c

@@ -946,7 +946,7 @@ bool meson_venc_hdmi_venc_repeat(int vic)
 EXPORT_SYMBOL_GPL(meson_venc_hdmi_venc_repeat);
 
 void meson_venc_hdmi_mode_set(struct meson_drm *priv, int vic,
-			      struct drm_display_mode *mode)
+			      const struct drm_display_mode *mode)
 {
 	union meson_hdmi_venc_mode *vmode = NULL;
 	union meson_hdmi_venc_mode vmode_dmt;

drivers/gpu/drm/meson/meson_venc.h

@@ -60,7 +60,7 @@ extern struct meson_cvbs_enci_mode meson_cvbs_enci_ntsc;
 void meson_venci_cvbs_mode_set(struct meson_drm *priv,
 			       struct meson_cvbs_enci_mode *mode);
 void meson_venc_hdmi_mode_set(struct meson_drm *priv, int vic,
-			      struct drm_display_mode *mode);
+			      const struct drm_display_mode *mode);
 unsigned int meson_venci_get_field(struct meson_drm *priv);
 
 void meson_venc_enable_vsync(struct meson_drm *priv);