fix disk bootup on qemu-arm

target/linux/config/Config.in.block

@@ -177,6 +177,7 @@ config ADK_KERNEL_ATA_PIIX
 	select ADK_KERNEL_ATA_BMDMA
 	select ADK_KERNEL_BLK_DEV
 	select ADK_KERNEL_BLK_DEV_SD
+	default y if ADK_TARGET_SYSTEM_QEMU_ARM
 	default y if ADK_TARGET_SYSTEM_QEMU_I686
 	default y if ADK_TARGET_SYSTEM_QEMU_MIPS
 	default y if ADK_TARGET_SYSTEM_QEMU_MIPSEL