fix jvc cdrom drive lockup

Before calling init_hwif_default, ide_unregister gets lock ide_lock and
disables irq.  init_hwif_default calls ide_default_io_base which calls
pci_get_device and later pci_get_subsys tries to apply for semaphore
pci_bus_sem and goes to sleep.

Mostly, pci_get_device should be called when irq is turned on.

ide_default_io_base just needs find if list pci_devices is empty.

Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>
Cc: Greg KH <greg@kroah.com>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/pci/probe.c

@@ -22,6 +22,18 @@ EXPORT_SYMBOL(pci_root_buses);
 
 LIST_HEAD(pci_devices);
 
+/*
+ * Some device drivers need know if pci is initiated.
+ * Basically, we think pci is not initiated when there
+ * is no device in list of pci_devices.
+ */
+int no_pci_devices(void)
+{
+	return list_empty(&pci_devices);
+}
+
+EXPORT_SYMBOL(no_pci_devices);
+
 #ifdef HAVE_PCI_LEGACY
 /**
  * pci_create_legacy_files - create legacy I/O port and memory files