regulator: core: Fix comment for regulator_register()

regulator_register() does not return 0 on success, fix the comment.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

drivers/regulator/core.c

@@ -3321,7 +3321,8 @@ static void rdev_init_debugfs(struct regulator_dev *rdev)
  * @config: runtime configuration for regulator
  *
  * Called by regulator drivers to register a regulator.
- * Returns 0 on success.
+ * Returns a valid pointer to struct regulator_dev on success
+ * or an ERR_PTR() on error.
  */
 struct regulator_dev *
 regulator_register(const struct regulator_desc *regulator_desc,