regulator: max8998: Ensure enough delay time for max8998_set_voltage_buck_time_sel

Use DIV_ROUND_UP to prevent truncation by integer division issue.
This ensures we return enough delay time.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: stable@vger.kernel.org

drivers/regulator/max8998.c

@@ -447,7 +447,7 @@ static int max8998_set_voltage_buck_time_sel(struct regulator_dev *rdev,
 
 	difference = (new_selector - old_selector) * desc->step / 1000;
 	if (difference > 0)
-		return difference / ((val & 0x0f) + 1);
+		return DIV_ROUND_UP(difference, (val & 0x0f) + 1);
 
 	return 0;
 }