Some work on the ATA/ATAPI seek feature and related changes
- now using the more accurate name "seek latency"
- fixed CD-ROM LBA address range checks and renamed limit to "max_lba"
- make the latency for CD-ROM access variable depending on the distance between
  current and new block address, Maximum value should only occur at first access
  or after media change.
- TODO: make hard disk seek timing variable, too.
- still TODO: seek latency for USB drives (requires asynchronus packet support).


git-svn-id: svn://svn.code.sf.net/p/bochs/code/trunk@12175 6c8e4198-a580-4521-a02f-c9ae86df1db9