regulator: max8998: Ensure enough delay time for max8998_set_voltage_buck_time_sel

commit 81d0a6ae upstream.

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>
[bwh: Backported to 3.2: delay is done by driver, not returned to the caller]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/regulator/max8998.c

@@ -497,7 +497,7 @@ static int max8998_set_voltage_buck(struct regulator_dev *rdev,
 
 	difference = desc->min + desc->step*i - previous_vol/1000;
 	if (difference > 0)
-		udelay(difference / ((val & 0x0f) + 1));
+		udelay(DIV_ROUND_UP(difference, (val & 0x0f) + 1));
 
 	return ret;
 }