- no need to zero drive->capacity48 and drive->select.b.lba
- don't call idedisk_read_native_max_address_ext() twice
  if drive uses LBA-48 and CONFIG_IDEDISK_STROKE is defined
- remove uneccessary setup of drive->capacity48/cyl/select.b.lba
  if drive uses LBA-48, maximum virtual LBA address needs to be set
  and CONFIG_IDEDISK_STROKE is defined
- set drive->cyl only once if drive uses LBA-48
- don't call idedisk_read_native_max_address() if drive uses LBA-48
  and don't call it twice if CONFIG_IDEDISK_STROKE is defined
- don't check for Host Protected Area if drive uses CHS addressing
  (such combination is not supported by a driver)
- remove duplicated code (at the end of the function) that is never executed