REGULATOR Handle positive returncode from enable

This makes _regulator_enable() properly handle the case where
a regulator is already on when you try to enable it. Currently
it will erroneously handle positive return values as an error.
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

drivers/regulator/core.c

@@ -1236,11 +1236,12 @@ static int _regulator_enable(struct regulator_dev *rdev)
 			} else {
 				return -EINVAL;
 			}
-		} else {
+		} else if (ret < 0) {
 			printk(KERN_ERR "%s: is_enabled() failed for %s: %d\n",
 			       __func__, rdev->desc->name, ret);
 			return ret;
 		}
+		/* Fallthrough on positive return values - already enabled */
 	}
 
 	rdev->use_count++;