MAINTAINERS: move old ide-{floppy,tape} entries to CREDITS (take 2)

Ben Hutchings noticed that MAINTAINERS somehow still contain old
ide-{floppy,tape} entries.  Fix it by moving them to CREDITS (kudos
to Gadi and Paul for all the early hard work on ide-{floppy,tape}).

v2:
Rename IDE/ATAPI CDROM DRIVER entry to IDE/ATAPI DRIVERS one.

Cc: Gadi Oxman <gadio@netvision.net.il>
Cc: Paul Bristow <paul@paulbristow.net>
Acked-by: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>