regulator: Only apply voltage constraints from consumers that set them

When applying the set_voltage() requests from consumers skip over those
consumers that haven't set anything, otherwise we'll come out with a
maximum voltage of zero.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

drivers/regulator/core.c

@@ -158,6 +158,13 @@ static int regulator_check_consumers(struct regulator_dev *rdev,
 	struct regulator *regulator;
 
 	list_for_each_entry(regulator, &rdev->consumer_list, list) {
+		/*
+		 * Assume consumers that didn't say anything are OK
+		 * with anything in the constraint range.
+		 */
+		if (!regulator->min_uV && !regulator->max_uV)
+			continue;
+
 		if (*max_uV > regulator->max_uV)
 			*max_uV = regulator->max_uV;
 		if (*min_uV < regulator->min_uV)