ide: split off ioctl handling from IDE settings (v2)

* do write permission and min/max checks in ide_procset_t functions

* ide-disk.c: drive->id is always available so cleanup "multcount" setting
  accordingly

* ide-disk.c: "address" setting was incorrectly defined as type TYPE_INTA,
  fix it by using type TYPE_BYTE and updating ide_drive_t->adressing field,
  the bug didn't trigger because this IDE setting uses custom ->set function

* ide.c: add set_ksettings() for handling HDIO_SET_KEEPSETTINGS ioctl

* ide.c: add set_unmaskirq() for handling HDIO_SET_UNMASKINTR ioctl

* handle ioctls directly in generic_ide_ioclt() and idedisk_ioctl()
  instead of using IDE settings to deal with them

* remove no longer needed ide_find_setting_by_ioctl() and {read,write}_ioctl
  fields from ide_settings_t, also remove now unused TYPE_INTA handling

v2:
* add missing EXPORT_SYMBOL_GPL(ide_setting_sem) needed now for ide-disk

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>