gpio: mvebu: Use IS_REACHABLE instead of IS_ENABLED for CONFIG_PWM

To check if a certain function (here e.g. pwmchip_add()) can be called
IS_REACHABLE is the better check. The relevant difference to IS_ENABLED
is that IS_REACHABLE evaluates to 0 if the current code is builtin but the
checked symbol is =m and so must not be used.

Today there is no practical impact as CONFIG_PWM is a bool.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

drivers/gpio/gpio-mvebu.c

@@ -1002,7 +1002,7 @@ static int mvebu_gpio_suspend(struct platform_device *pdev, pm_message_t state)
 		BUG();
 	}
 
-	if (IS_ENABLED(CONFIG_PWM))
+	if (IS_REACHABLE(CONFIG_PWM))
 		mvebu_pwm_suspend(mvchip);
 
 	return 0;
@@ -1054,7 +1054,7 @@ static int mvebu_gpio_resume(struct platform_device *pdev)
 		BUG();
 	}
 
-	if (IS_ENABLED(CONFIG_PWM))
+	if (IS_REACHABLE(CONFIG_PWM))
 		mvebu_pwm_resume(mvchip);
 
 	return 0;
@@ -1228,7 +1228,7 @@ static int mvebu_gpio_probe(struct platform_device *pdev)
 	devm_gpiochip_add_data(&pdev->dev, &mvchip->chip, mvchip);
 
 	/* Some MVEBU SoCs have simple PWM support for GPIO lines */
-	if (IS_ENABLED(CONFIG_PWM)) {
+	if (IS_REACHABLE(CONFIG_PWM)) {
 		err = mvebu_pwm_probe(pdev, mvchip, id);
 		if (err)
 			return err;