Input: max77693-haptic - fix potential overflow

Expression haptic->pwm_dev->period * haptic->magnitude is of type
'unsigned int' and may overflow. We need to convert one of the operands
to u64 before multiplying, instead of casting result (potentially
overflown) to u64.

Reported by Coverity: CID 1248753

Acked-by : Jaewon Kim <jaewon02.kim@samsung.com>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/misc/max77693-haptic.c

@@ -194,7 +194,7 @@ static int max77693_haptic_play_effect(struct input_dev *dev, void *data,
 				       struct ff_effect *effect)
 {
 	struct max77693_haptic *haptic = input_get_drvdata(dev);
-	uint64_t period_mag_multi;
+	u64 period_mag_multi;
 
 	haptic->magnitude = effect->u.rumble.strong_magnitude;
 	if (!haptic->magnitude)
@@ -205,8 +205,7 @@ static int max77693_haptic_play_effect(struct input_dev *dev, void *data,
 	 * The formula to convert magnitude to pwm_duty as follows:
 	 * - pwm_duty = (magnitude * pwm_period) / MAX_MAGNITUDE(0xFFFF)
 	 */
-	period_mag_multi = (int64_t)(haptic->pwm_dev->period *
-						haptic->magnitude);
+	period_mag_multi = (u64)haptic->pwm_dev->period * haptic->magnitude;
 	haptic->pwm_duty = (unsigned int)(period_mag_multi >>
 						MAX_MAGNITUDE_SHIFT);