serial: Replace CONFIG_ with CONFIG_IS_ENABLED

Cosmetic change, replace CONFIG_* with CONFIG_IS_ENABLED(*) .

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
diff --git a/drivers/serial/serial_sh.c b/drivers/serial/serial_sh.c
index c07ddc7..a17698f 100644
--- a/drivers/serial/serial_sh.c
+++ b/drivers/serial/serial_sh.c
@@ -149,7 +149,7 @@
 	return ch;
 }
 
-#ifdef CONFIG_DM_SERIAL
+#if CONFIG_IS_ENABLED(DM_SERIAL)
 
 static int sh_serial_pending(struct udevice *dev, bool input)
 {
@@ -204,7 +204,7 @@
 	.setbrg = sh_serial_setbrg,
 };
 
-#ifdef CONFIG_OF_CONTROL
+#if CONFIG_IS_ENABLED(OF_CONTROL)
 static const struct udevice_id sh_serial_id[] ={
 	{.compatible = "renesas,sci", .data = PORT_SCI},
 	{.compatible = "renesas,scif", .data = PORT_SCIF},