Original patch from Erik Andersen <andersen@codepoet.org>:
- fix CONFIG_IDEDISK_STROKE by adding proper detection of HPA feature set
  and removing IDE_STROKE_LIMIT
- remove irrelevant idedisk_supports_host_protected_area()
- make the HPA detection actually display useful information

I've reworked it a bit:
- detect HPA before calculating drive's geometry
- move HPA detection outside init_idedisk_capacity()
  to idedisk_check_hpa_lba28() and idedisk_check_hpa_lba48()
- use sectors_to_MB()
- respect 80-column limit