drm/bridge/tfp410: Make symbol tfp410_platform_driver static

Fixes the following sparse warning:

drivers/gpu/drm/bridge/ti-tfp410.c:223:24: warning:
 symbol 'tfp410_platform_driver' was not declared. Should it be static?
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20170209152549.30711-1-weiyj.lk@gmail.com

drivers/gpu/drm/bridge/ti-tfp410.c

@@ -220,7 +220,7 @@ static const struct of_device_id tfp410_match[] = {
 };
 MODULE_DEVICE_TABLE(of, tfp410_match);
 
-struct platform_driver tfp410_platform_driver = {
+static struct platform_driver tfp410_platform_driver = {
 	.probe	= tfp410_probe,
 	.remove	= tfp410_remove,
 	.driver	= {