phy: ti: am654-serdes: Make serdes_am654_xlate() static

Fix sparse warning:

drivers/phy/ti/phy-am654-serdes.c:250:12: warning:
 symbol 'serdes_am654_xlate' was not declared. Should it be static?
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

drivers/phy/ti/phy-am654-serdes.c

@@ -247,8 +247,8 @@ static void serdes_am654_release(struct phy *x)
 	mux_control_deselect(phy->control);
 }
 
-struct phy *serdes_am654_xlate(struct device *dev, struct of_phandle_args
-				 *args)
+static struct phy *serdes_am654_xlate(struct device *dev,
+				      struct of_phandle_args *args)
 {
 	struct serdes_am654 *am654_phy;
 	struct phy *phy;