Some people want to use ide_cd for CD-ROM but still dynamically load
ide-scsi for things like tape drives.  If you compile in the CD driver this
works out but if you want them modular you need an option to ensure that
whoever loads first the right things happen.

This replaces the original draft patch which leaked a scsi host reference

[akpm@osdl.org: add MODULE_PARM_DESC]
Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>