regulator: core: Say what unsupportable voltage constraints are

Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>

drivers/regulator/core.c

@@ -883,7 +883,9 @@ static int machine_constraints_voltage(struct regulator_dev *rdev,
 
 		/* final: [min_uV..max_uV] valid iff constraints valid */
 		if (max_uV < min_uV) {
-			rdev_err(rdev, "unsupportable voltage constraints\n");
+			rdev_err(rdev,
+				 "unsupportable voltage constraints %u-%uuV\n",
+				 min_uV, max_uV);
 			return -EINVAL;
 		}