ppc/ppc4xx: remove ppc_ide_md hooks

There are no "default" IDE ports on PPC4xx so ppc4xx_ide_init_hwif_ports() is
unnecessary, remove it.  Also remove no longer needed <linux/ide.h> include.

There should be no functional changes caused by this patch.

Cc: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>