drm/panel: ld9040: Add dummy prepare and unprepare routines

This patch adds dummy definition for prepare and unprepare
routines to ld9040 panel driver.
Signed-off-by: Ajay Kumar <ajaykumar.rs@samsung.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/panel/panel-ld9040.c

@@ -228,6 +228,16 @@ static int ld9040_disable(struct drm_panel *panel)
 	return ld9040_power_off(ctx);
 }
 
+static int ld9040_unprepare(struct drm_panel *panel)
+{
+	return 0;
+}
+
+static int ld9040_prepare(struct drm_panel *panel)
+{
+	return 0;
+}
+
 static int ld9040_enable(struct drm_panel *panel)
 {
 	struct ld9040 *ctx = panel_to_ld9040(panel);
@@ -273,6 +283,8 @@ static int ld9040_get_modes(struct drm_panel *panel)
 
 static const struct drm_panel_funcs ld9040_drm_funcs = {
 	.disable = ld9040_disable,
+	.unprepare = ld9040_unprepare,
+	.prepare = ld9040_prepare,
 	.enable = ld9040_enable,
 	.get_modes = ld9040_get_modes,
 };