pwm: sun4i: Initialize variables before use

GCC can't always determine that the duty, period and prescaler values
are initialized when returning from sun4i_pwm_calculate(), so help out a
little by initializing them to 0.
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-sun4i.c

@@ -234,9 +234,9 @@ static int sun4i_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 {
 	struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
 	struct pwm_state cstate;
-	u32 ctrl, duty, period, val;
+	u32 ctrl, duty = 0, period = 0, val;
 	int ret;
-	unsigned int delay_us, prescaler;
+	unsigned int delay_us, prescaler = 0;
 	unsigned long now;
 	bool bypass;