regulator: Clarify documentation for regmap in the config

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

include/linux/regulator/driver.h

@@ -221,7 +221,8 @@ struct regulator_desc {
  * @driver_data: private regulator data
  * @of_node: OpenFirmware node to parse for device tree bindings (may be
  *           NULL).
- * @regmap: regmap to use for core regmap helpers
+ * @regmap: regmap to use for core regmap helpers if dev_get_regulator() is
+ *          insufficient.
  * @ena_gpio: GPIO controlling regulator enable.
  * @ena_gpio_invert: Sense for GPIO enable control.
  * @ena_gpio_flags: Flags to use when calling gpio_request_one()