- fix bug introduced in IDE 63 in ide_do_drive_cmd(), if action is ide_end
  request should be added to end of queue not next to current request,
  fortunately it is used only by ide-tape which is broken anyway

- fix bug introduced in IDE 94 in idedisk_do_request(), removal of
  rq->special = ar; probably needed by PMAC and TCQ

- fix bug introduced in IDE 94 in do_request(), always setting IDE_BUSY
  bit could lead to deadlock

- disable ide__sti() in do_request(), doing __sti() while holding irqsaving
  spinlock is not good idea

- in check_crc_errors() do strict checking for UDMA modes

- clean double setting handler/timer hack

- in ide_do_drive_cmd() hold channel lock only if action is ide_wait