drm/panel: panasonic-vvx10f034n00: Fix wuxga_nt_panel_disable() return value

Return value for mipi_dsi_shutdown_peripheral() is unchecked.
Check it and return any errors if they come up. Even if
mipi_dsi_shutdown_peripheral() fails, continue attempting to
disable.

Cc: Philippe Cornu <philippe.cornu@st.com>
Reviewed-by: Philippe Cornu <philippe.cornu@st.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180116222217.240939-1-seanpaul@chromium.org

drivers/gpu/drm/panel/panel-panasonic-vvx10f034n00.c

@@ -72,11 +72,12 @@ static int wuxga_nt_panel_on(struct wuxga_nt_panel *wuxga_nt)
 static int wuxga_nt_panel_disable(struct drm_panel *panel)
 {
 	struct wuxga_nt_panel *wuxga_nt = to_wuxga_nt_panel(panel);
+	int ret;
 
 	if (!wuxga_nt->enabled)
 		return 0;
 
-	mipi_dsi_shutdown_peripheral(wuxga_nt->dsi);
+	ret = mipi_dsi_shutdown_peripheral(wuxga_nt->dsi);
 
 	if (wuxga_nt->backlight) {
 		wuxga_nt->backlight->props.power = FB_BLANK_POWERDOWN;
@@ -86,7 +87,7 @@ static int wuxga_nt_panel_disable(struct drm_panel *panel)
 
 	wuxga_nt->enabled = false;
 
-	return 0;
+	return ret;
 }
 
 static int wuxga_nt_panel_unprepare(struct drm_panel *panel)