regulator: fix header file missing kernel-doc

Fix regulator/driver.h missing kernel-doc:

Warning(linux-next-20090120//include/linux/regulator/driver.h:108): No description found for parameter 'get_status'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
cc: Liam Girdwood <lrg@slimlogic.co.uk>
cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

include/linux/regulator/driver.h

@@ -51,6 +51,7 @@ enum regulator_status {
  *
  * @set_mode: Set the operating mode for the regulator.
  * @get_mode: Get the current operating mode for the regulator.
+ * @get_status: Report the regulator status.
  * @get_optimum_mode: Get the most efficient operating mode for the regulator
  *                    when running with the specified parameters.
  *