ide: remove CONFIG_IDE_ARCH_OBSOLETE_INIT

* Use CONFIG_IDE_ARCH_OBSOLETE_DEFAULTS instead of
  CONFIG_IDE_ARCH_OBSOLETE_INIT in init_ide_data().

* Remove no longer needed CONFIG_IDE_ARCH_OBSOLETE_INIT.

There should be no functional changes caused by this patch.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>