regulator: core: Slightly improve readability of _regulator_get_enable_time

The logic is equivalent, but it looks more straightforward this way:
If rdev->desc->ops->enable_time is set, call it.
Otherwise fallback to return rdev->desc->enable_time.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -1650,9 +1650,9 @@ static int _regulator_get_enable_time(struct regulator_dev *rdev)
 {
 	if (rdev->constraints && rdev->constraints->enable_time)
 		return rdev->constraints->enable_time;
-	if (!rdev->desc->ops->enable_time)
-		return rdev->desc->enable_time;
-	return rdev->desc->ops->enable_time(rdev);
+	if (rdev->desc->ops->enable_time)
+		return rdev->desc->ops->enable_time(rdev);
+	return rdev->desc->enable_time;
 }
 
 static struct regulator_supply_alias *regulator_find_supply_alias(