powerpc/ide: remove mpc8xx-ide driver

This driver was only used by arch/ppc code and is obsolete
now with the move to common arch/powerpc code.

[bart: port it over IDE tree, remove leftover 'choice' from Kconfig]

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>