hw/ide/ahci: Add a Kconfig switch for the AHCI-ICH9 device

Some of our machines (like the ARM cubieboard) use CONFIG_AHCI for an AHCI
sysbus device, but do not use CONFIG_PCI since they do not feature a PCI
bus. With CONFIG_AHCI but without CONFIG_PCI, currently linking fails:

    ../hw/ide/ich.o: In function `pci_ich9_ahci_realize':
    hw/ide/ich.c:124: undefined reference to `pci_allocate_irq'
    hw/ide/ich.c:126: undefined reference to `pci_register_bar'
    hw/ide/ich.c:128: undefined reference to `pci_register_bar'
    hw/ide/ich.c:131: undefined reference to `pci_add_capability'
    hw/ide/ich.c:147: undefined reference to `msi_init'
    ../hw/ide/ich.o: In function `pci_ich9_uninit':
    hw/ide/ich.c:158: undefined reference to `msi_uninit'
    ../hw/ide/ich.o:(.data.rel+0x50): undefined reference to `vmstate_pci_device'

We must only compile ich.c if CONFIG_PCI is available, too, so introduce a
new config switch for this device.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: John Snow <jsnow@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

hw/i386/Kconfig

@@ -80,7 +80,7 @@ config Q35
     select PC_ACPI
     select PCI_EXPRESS_Q35
     select LPC_ICH9
-    select AHCI
+    select AHCI_ICH9
     select DIMM
     select SMBIOS
     select VMPORT

hw/ide/Kconfig

@@ -43,10 +43,14 @@ config MICRODRIVE
     select IDE_QDEV
 
 config AHCI
+    bool
+    select IDE_QDEV
+
+config AHCI_ICH9
     bool
     default y if PCI_DEVICES
     depends on PCI
-    select IDE_QDEV
+    select AHCI
 
 config IDE_SII3112
     bool

hw/ide/Makefile.objs

@@ -9,6 +9,6 @@ common-obj-$(CONFIG_IDE_MMIO) += mmio.o
 common-obj-$(CONFIG_IDE_VIA) += via.o
 common-obj-$(CONFIG_MICRODRIVE) += microdrive.o
 common-obj-$(CONFIG_AHCI) += ahci.o
-common-obj-$(CONFIG_AHCI) += ich.o
+common-obj-$(CONFIG_AHCI_ICH9) += ich.o
 common-obj-$(CONFIG_ALLWINNER_A10) += ahci-allwinner.o
 common-obj-$(CONFIG_IDE_SII3112) += sii3112.o