disp: msm: dsi: do not enable PWM when setting bl to 0

Check backlight value, if it's 0, do not enable PWM.

Change-Id: I6fccb42555731bf3faa88a93cbf1a36a417ff49d
Signed-off-by: Zhao, Yuan <yzhao@codeaurora.org>

msm/dsi/dsi_panel.c

@@ -572,7 +572,7 @@ static int dsi_panel_update_pwm_backlight(struct dsi_panel *panel,
 		return 0;
 	}
 
-	if (!bl->pwm_enabled) {
+	if (bl_lvl != 0 && !bl->pwm_enabled) {
 		rc = pwm_enable(bl->pwm_bl);
 		if (rc) {
 			DSI_ERR("[%s] failed to enable pwm, rc=\n", panel->name,