drm/panel: ld9040: Add proper definition for prepare and unprepare

Move out code from enable and disable routines to prepare
and unprepare routines, so that functionality is properly
distributed across all the panel functions.
Signed-off-by: NAjay Kumar <ajaykumar.rs@samsung.com>
Signed-off-by: NThierry Reding <treding@nvidia.com>

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

@@ -215,6 +215,11 @@ static int ld9040_power_off(struct ld9040 *ctx)
 }
 
 static int ld9040_disable(struct drm_panel *panel)
+{
+	return 0;
+}
+
+static int ld9040_unprepare(struct drm_panel *panel)
 {
 	struct ld9040 *ctx = panel_to_ld9040(panel);
 
@@ -228,17 +233,7 @@ 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);
 	int ret;
@@ -252,11 +247,16 @@ static int ld9040_enable(struct drm_panel *panel)
 	ret = ld9040_clear_error(ctx);
 
 	if (ret < 0)
-		ld9040_disable(panel);
+		ld9040_unprepare(panel);
 
 	return ret;
 }
 
+static int ld9040_enable(struct drm_panel *panel)
+{
+	return 0;
+}
+
 static int ld9040_get_modes(struct drm_panel *panel)
 {
 	struct drm_connector *connector = panel->connector;