GPU-DRM-IMX: Delete an unnecessary check before drm_fbdev_cma_restore_mode()

The drm_fbdev_cma_restore_mode() function tests whether its argument
is NULL and then returns immediately.
Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

drivers/gpu/drm/imx/imx-drm-core.c

@@ -63,8 +63,7 @@ static void imx_drm_driver_lastclose(struct drm_device *drm)
 #if IS_ENABLED(CONFIG_DRM_IMX_FB_HELPER)
 	struct imx_drm_device *imxdrm = drm->dev_private;
 
-	if (imxdrm->fbhelper)
-		drm_fbdev_cma_restore_mode(imxdrm->fbhelper);
+	drm_fbdev_cma_restore_mode(imxdrm->fbhelper);
 #endif
 }