ppc/pplus: remove ppc_ide_md.ide_init_hwif hook

* Call ide_init_default_irq() for pplus in init_ide_data().

* Remove no longer needed pplus_ide_init_hwif_ports().

There should be no functional changes caused by this patch.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>