ide: use IDE_TFLAG_LBA48 for REQ_TYPE_ATA_TASKFILE requests

* Use IDE_TFLAG_LBA48 for REQ_TYPE_ATA_TASKFILE requests in ide_end_drive_cmd()
  to decide whether we need to read HOB taskfile registers.

* Update execute_drive_cmd() accordingly.

This is a preparation for the next patch which removes unnecessary writes to
HOB taskfile registers for some ATA commands.

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