pwm-sun4i: Calculate "delay_jiffies" directly, eliminate absolute time

Basically this code did "jiffies + period - jiffies", and we can
simply eliminate the "jiffies" time stamp here.

Signed-off-by: Max Kellermann <[e-mail]>
Acked-by: Uwe Kleine-König <[e-mail]>
Signed-off-by: Thierry Reding <[e-mail]>

drivers/pwm/pwm-sun4i.c

···
 	struct pwm_state cstate;
 	u32 ctrl, duty = 0, period = 0, val;
 	int ret;
+	unsigned int delay_jiffies;
 	unsigned int delay_us, prescaler = 0;
-	unsigned long now;
-	unsigned long next_period;
 	bool bypass;
 
 	pwm_get_state(pwm, &cstate);
···
 
 	val = (duty & PWM_DTY_MASK) | PWM_PRD(period);
 	sun4i_pwm_writel(sun4i_pwm, val, PWM_CH_PRD(pwm->hwpwm));
-	next_period = jiffies +
-		nsecs_to_jiffies(cstate.period + 1000);
 
 	if (state->polarity != PWM_POLARITY_NORMAL)
 		ctrl &= ~BIT_CH(PWM_ACT_STATE, pwm->hwpwm);
···
 		return 0;
 
 	/* We need a full period to elapse before disabling the channel. */
-	now = jiffies;
-	if (time_before(now, next_period)) {
-		delay_us = jiffies_to_usecs(next_period - now);
-		if ((delay_us / 500) > MAX_UDELAY_MS)
-			msleep(delay_us / 1000 + 1);
-		else
-			usleep_range(delay_us, delay_us * 2);
-	}
+	delay_jiffies = nsecs_to_jiffies(cstate.period + 1000);
+	delay_us = jiffies_to_usecs(delay_jiffies);
+	if ((delay_us / 500) > MAX_UDELAY_MS)
+		msleep(delay_us / 1000 + 1);
+	else
+		usleep_range(delay_us, delay_us * 2);
 
 	spin_lock(&sun4i_pwm->ctrl_lock);
 	ctrl = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);