pwm: Add the pwm_is_enabled() helper

Some PWM drivers are testing the PWMF_ENABLED flag. Create a helper
function to hide the logic behind enabled test. This will allow us to
smoothly move from the current approach to an atomic PWM update
approach.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
diff --git a/drivers/pwm/pwm-tiehrpwm.c b/drivers/pwm/pwm-tiehrpwm.c
index 694b3cf..6a41e66 100644
--- a/drivers/pwm/pwm-tiehrpwm.c
+++ b/drivers/pwm/pwm-tiehrpwm.c
@@ -407,7 +407,7 @@
 {
 	struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);
 
-	if (test_bit(PWMF_ENABLED, &pwm->flags)) {
+	if (pwm_is_enabled(pwm)) {
 		dev_warn(chip->dev, "Removing PWM device without disabling\n");
 		pm_runtime_put_sync(chip->dev);
 	}
@@ -565,7 +565,7 @@
 	for (i = 0; i < pc->chip.npwm; i++) {
 		struct pwm_device *pwm = &pc->chip.pwms[i];
 
-		if (!test_bit(PWMF_ENABLED, &pwm->flags))
+		if (!pwm_is_enabled(pwm))
 			continue;
 
 		/* Disable explicitly if PWM is running */
@@ -582,7 +582,7 @@
 	for (i = 0; i < pc->chip.npwm; i++) {
 		struct pwm_device *pwm = &pc->chip.pwms[i];
 
-		if (!test_bit(PWMF_ENABLED, &pwm->flags))
+		if (!pwm_is_enabled(pwm))
 			continue;
 
 		/* Enable explicitly if PWM was running */