ppc/sandpoint: remove ppc_ide_md hooks

ppc/sandpoint: remove ppc_ide_md hooks

* Add IDE_HFLAG_FORCE_LEGACY_IRQS host flag for Motorola-Sandpoint platform
  to sl82c105 host driver.

* Disable ide_generic host driver in arch/ppc/configs/sandpoint_defconfig
  and enable sl82c105 one.

* Remove ppc_ide_md hooks from arch/ppc/platforms/sandpoint.c - no need for
  them (sl82c105 host driver takes care of all this setup).

* Then remove no longer needed <linux/ide.h> include.

* Also update arch/ppc/platforms/sandpoint.h.

Unfortunately (unlike lopec's case) sl82c105 host driver was not enabled
in defconfing so there is a funcionality change.

[ Not a big deal since sl82c105 is superior over ide_generic. ]

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