pwm: tiehrpwm: don't build PM related functions when not needed

Fixes following warnings on AM335X with no PM_SLEEP

drivers/pwm/pwm-tiehrpwm.c:534:13: warning: 'ehrpwm_pwm_save_context' defined but not used [-Wunused-function]
drivers/pwm/pwm-tiehrpwm.c:548:13: warning: 'ehrpwm_pwm_restore_context' defined but not used [-Wunused-function]

Signed-off-by: Wolfram Sang <wsa@sang-engineering.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-tiehrpwm.c

@@ -529,6 +529,7 @@ static int ehrpwm_pwm_remove(struct platform_device *pdev)
 	return pwmchip_remove(&pc->chip);
 }
 
+#ifdef CONFIG_PM_SLEEP
 static void ehrpwm_pwm_save_context(struct ehrpwm_pwm_chip *pc)
 {
 	pm_runtime_get_sync(pc->chip.dev);
@@ -555,7 +556,6 @@ static void ehrpwm_pwm_restore_context(struct ehrpwm_pwm_chip *pc)
 	ehrpwm_write(pc->mmio_base, TBCTL, pc->ctx.tbctl);
 }
 
-#ifdef CONFIG_PM_SLEEP
 static int ehrpwm_pwm_suspend(struct device *dev)
 {
 	struct ehrpwm_pwm_chip *pc = dev_get_drvdata(dev);