spi: mediatek: mtk_spi_driver can be static

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/spi/spi-mt65xx.c b/drivers/spi/spi-mt65xx.c
index 4676b01..e62d304 100644
--- a/drivers/spi/spi-mt65xx.c
+++ b/drivers/spi/spi-mt65xx.c
@@ -731,7 +731,7 @@
 			   mtk_spi_runtime_resume, NULL)
 };
 
-struct platform_driver mtk_spi_driver = {
+static struct platform_driver mtk_spi_driver = {
 	.driver = {
 		.name = "mtk-spi",
 		.pm	= &mtk_spi_pm,