[ARM/IDE] Fix BLK_DEV_IDEDMA setting on non-Acorn ARM systems

Only default BLK_DEV_IDEDMA on BLK_DEV_IDEDMA_ICS if ARCH_ACORN is
set, not if ARM is set.  There are PCI ARM systems out there!

drivers/ide/Kconfig

@@ -376,7 +376,7 @@ config IDEDMA_ONLYDISK
 config BLK_DEV_IDEDMA
 	bool
 	depends on BLK_DEV_IDE
-	default BLK_DEV_IDEDMA_ICS if ARM
+	default BLK_DEV_IDEDMA_ICS if ARCH_ACORN
 	default BLK_DEV_IDEDMA_PMAC if ALL_PPC && BLK_DEV_IDE_PMAC
 	default BLK_DEV_IDEDMA_PCI if PCI && BLK_DEV_IDEPCI