OMAP: DSS2: don't power off a panel twice

If we blank the panel by
echo 1 > /sys/devices/platform/omapfb/graphics/fb0/blank

Then, we reboot the sytem, the kernel will crash at
drivers/video/omap2/dss/core.c:323

This is because the panel is closed twice. Now check the state of a dssdev
to forbid a panel is power on or power off twice.

Signed-off-by: Stanley.Miao <stanley.miao@windriver.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@nokia.com>
diff --git a/drivers/video/omap2/displays/panel-sharp-ls037v7dw01.c b/drivers/video/omap2/displays/panel-sharp-ls037v7dw01.c
index 7d9eb2b..9a138f6 100644
--- a/drivers/video/omap2/displays/panel-sharp-ls037v7dw01.c
+++ b/drivers/video/omap2/displays/panel-sharp-ls037v7dw01.c
@@ -135,6 +135,9 @@
 {
 	int r = 0;
 
+	if (dssdev->state == OMAP_DSS_DISPLAY_ACTIVE)
+		return 0;
+
 	r = omapdss_dpi_display_enable(dssdev);
 	if (r)
 		goto err0;
@@ -157,6 +160,9 @@
 
 static void sharp_ls_power_off(struct omap_dss_device *dssdev)
 {
+	if (dssdev->state != OMAP_DSS_DISPLAY_ACTIVE)
+		return;
+
 	if (dssdev->platform_disable)
 		dssdev->platform_disable(dssdev);