ide_reinit_drive() turned into ata_attach().  Said beast takes a drive,
tries to feed it to high-level drivers and drops it on the ata_unused if
nobody claims the sucker.  IOW, that's what ide_register_module() used
to do, but for a single drive.

ideprobe_init() calls ata_attach() instead of putting on ata_unused.

ide_register_module() eliminated.  Some of the callers do not need it
anymore, some (ide_replace_subdriver()) actually want ata_attach(drive).

ide_scan_devices() is gone.  There were two remaining callers - in
ide_register_module() and ide_unregister_module().  The former had been
turned into "put driver on the list, empty ata_unused into temporary
list and call ata_attach() on all drives there".  The latter is "remove
driver from the list, call ->cleanup() and ata_attach() for all drives"
(->cleanup() gives the drive up, ata_attach() gives the remaining
drivers a shot for that drive; if nobody claims it - it's put on
ata_unused).