serial: stm32: select pinctrl state in each suspend/resume function

Select either pinctrl sleep state in suspend function or default state in
resume function.
Signed-off-by: Bich Hemon <bich.hemon@st.com>
Signed-off-by: Erwan Le Ray <erwan.leray@st.com>

Link: https://lore.kernel.org/r/1560433800-12255-4-git-send-email-erwan.leray@st.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/stm32-usart.c

@@ -24,6 +24,7 @@
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_platform.h>
+#include <linux/pinctrl/consumer.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/pm_wakeirq.h>
@@ -1373,6 +1374,8 @@ static int stm32_serial_suspend(struct device *dev)
 	else
 		stm32_serial_enable_wakeup(port, false);
 
+	pinctrl_pm_select_sleep_state(dev);
+
 	return 0;
 }
 
@@ -1380,6 +1383,8 @@ static int stm32_serial_resume(struct device *dev)
 {
 	struct uart_port *port = dev_get_drvdata(dev);
 
+	pinctrl_pm_select_default_state(dev);
+
 	if (device_may_wakeup(dev))
 		stm32_serial_enable_wakeup(port, false);