regulator: Fix documentation for regmap in the config

dev_get_regulator() does not exist, fix the typo.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

include/linux/regulator/driver.h

@@ -316,7 +316,7 @@ 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 if dev_get_regulator() is
+ * @regmap: regmap to use for core regmap helpers if dev_get_regmap() is
  *          insufficient.
  * @ena_gpio_initialized: GPIO controlling regulator enable was properly
  *                        initialized, meaning that >= 0 is a valid gpio