ide: remove IDE_ARCH_INTR (v2)

This micro-optimization is not worth it.  Just always check for
existence of ->ack_intr method in ide_intr() and ide_timer_expiry().

v2:
Fix brown-paper-bag bug spotted by David D. Kilzer.

Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Michael Schmitz <schmitz@debian.org>
Cc: "David D. Kilzer" <ddkilzer@kilzer.net>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

arch/m68k/include/asm/ide.h

@@ -123,8 +123,5 @@ ide_get_lock(irq_handler_t handler, void *data)
 }
 #endif /* CONFIG_BLK_DEV_FALCON_IDE */
 
-#define IDE_ARCH_ACK_INTR
-#define ide_ack_intr(hwif)	((hwif)->ack_intr ? (hwif)->ack_intr(hwif) : 1)
-
 #endif /* __KERNEL__ */
 #endif /* _M68K_IDE_H */