ide: add CONFIG_IDE_ARCH_OBSOLETE_DEFAULTS (take 2)

* Add CONFIG_IDE_ARCH_OBSOLETE_DEFAULTS to drivers/ide/Kconfig and use
  it instead of defining IDE_ARCH_OBSOLETE_DEFAULTS in <arch/ide.h>.

v2:
* Define ide_default_irq() in ide-probe.c/ns87415.c if not already defined
  and drop defining ide_default_irq() for CONFIG_IDE_ARCH_OBSOLETE_DEFAULTS=n.

  [ Thanks to Stephen Rothwell and David Miller for noticing the problem. ]

Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/pci/ns87415.c b/drivers/ide/pci/ns87415.c
index bf0d3b2..75513320 100644
--- a/drivers/ide/pci/ns87415.c
+++ b/drivers/ide/pci/ns87415.c
@@ -181,6 +181,10 @@
 	return 1;
 }
 
+#ifndef ide_default_irq
+#define ide_default_irq(irq) 0
+#endif
+
 static void __devinit init_hwif_ns87415 (ide_hwif_t *hwif)
 {
 	struct pci_dev *dev = to_pci_dev(hwif->dev);