powerpc/85xx: disable IDE subsystem in ksi8560_defconfig

This patch disables deprecated IDE subsystem in ksi8560_defconfig
(no IDE host drivers are selected in this config so there is no valid
reason to enable IDE subsystem itself).

Cc: Scott Wood <oss@buserror.net>
Cc: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Scott Wood <oss@buserror.net>

arch/powerpc/configs/85xx/ksi8560_defconfig

@@ -34,7 +34,6 @@ CONFIG_MTD_PHYSMAP_OF=y
 CONFIG_BLK_DEV_LOOP=y
 CONFIG_BLK_DEV_RAM=y
 CONFIG_BLK_DEV_RAM_SIZE=32768
-CONFIG_IDE=y
 CONFIG_NETDEVICES=y
 CONFIG_FS_ENET=y
 # CONFIG_FS_ENET_HAS_SCC is not set