drm/fb-helper: generic: Call drm_client_add() after setup is done

Hotplug can happen while drm_fbdev_generic_setup() is running so move
drm_client_add() call after setup is done to avoid
drm_fbdev_client_hotplug() running in two threads at the same time.

Fixes: 9060d7f49376 ("drm/fb-helper: Finish the generic fbdev emulation")
Cc: [e-mail]
Reported-by: Daniel Vetter <[e-mail]>
Signed-off-by: Noralf Trønnes <[e-mail]>
Reviewed-by: Daniel Vetter <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/drm_fb_helper.c

···
 		return ret;
 	}
 
-	drm_client_add(&fb_helper->client);
-
 	if (!preferred_bpp)
 		preferred_bpp = dev->mode_config.preferred_depth;
 	if (!preferred_bpp)
···
 	ret = drm_fbdev_client_hotplug(&fb_helper->client);
 	if (ret)
 		DRM_DEV_DEBUG(dev->dev, "client hotplug ret=%d\n", ret);
+
+	drm_client_add(&fb_helper->client);
 
 	return 0;
 }