drm/exynos: Fix double locks at PM resume

The recent commit [3ea87855: drm/helper: lock all around force mode
restore] introduced drm_modeset_lock_all() in
drm_helper_resume_force_mode() itself, while exynos driver takes this
lock before calling it.  Move the function call outside the lock for
avoiding a deadlock.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NInki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_drv.c

@@ -182,9 +182,9 @@ static int exynos_drm_resume(struct drm_device *dev)
 		if (connector->funcs->dpms)
 			connector->funcs->dpms(connector, connector->dpms);
 	}
+	drm_modeset_unlock_all(dev);
 
 	drm_helper_resume_force_mode(dev);
-	drm_modeset_unlock_all(dev);
 
 	return 0;
 }