regulator: fix kernel-doc warnings in drivers/regulator/core.c

Fix regulator kernel-doc warnings:

Warning(drivers/regulator/core.c:2308): No description found for parameter 'rdev'
Warning(drivers/regulator/core.c:2308): Excess function parameter 'regulator' description in 'regulator_set_voltage_time_sel'

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Cc:	Liam Girdwood <lrg@ti.com>
Cc:	Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

drivers/regulator/core.c

@@ -2291,8 +2291,8 @@ int regulator_set_voltage_time(struct regulator *regulator,
 EXPORT_SYMBOL_GPL(regulator_set_voltage_time);
 
 /**
- *regulator_set_voltage_time_sel - get raise/fall time
- * @regulator: regulator source
+ * regulator_set_voltage_time_sel - get raise/fall time
+ * @rdev: regulator source device
  * @old_selector: selector for starting voltage
  * @new_selector: selector for target voltage
  *