regulator: fix kernel-doc warnings

Fix kernel-doc warnings in regulator/driver.h:

Warning(linux-next-20090108//include/linux/regulator/driver.h:95): Excess struct/union/enum/typedef member 'set_current' description in 'regulator_ops'
Warning(linux-next-20090108//include/linux/regulator/driver.h:95): Excess struct/union/enum/typedef member 'get_current' description in 'regulator_ops'
Warning(linux-next-20090108//include/linux/regulator/driver.h:124): No description found for parameter 'irq'

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>