ide: add ide_init_port_hw() helper

* Add ide_init_port_hw() helper.

* rapide.c: convert rapide_locate_hwif() to rapide_setup_ports()
  and use ide_init_port_hw().

* ide_platform.c: convert plat_ide_locate_hwif() to plat_ide_setup_ports()
  and use ide_init_port_hw().

* sgiioc4.c: use ide_init_port_hw().

* pmac.c: add 'hw_regs_t *hw' argument to pmac_ide_setup_device(),
  setup 'hw' in pmac_ide_{macio,pci}_attach() and use ide_init_port_hw()
  in pmac_ide_setup_device().

This patch is a preparation for the future changes in the IDE probing code.

There should be no functionality changes caused by this patch.

Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Anton Vorontsov <avorontsov@ru.mvista.com>
Cc: Jeremy Higdon <jeremy@sgi.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>