driver core: remove fields from struct bus_type

struct bus_type is static everywhere in the kernel.  This moves the
kobject in the structure out of it, and a bunch of other private only to
the driver core fields are now moved to a private structure.  This lets
us dynamically create the backing kobject properly and gives us the
chance to be able to document to users exactly how to use the struct
bus_type as there are no fields they can improperly access.

Thanks to Kay for the build fixes on this patch.

Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 7ac474d..7bf0e67 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -38,7 +38,7 @@
 		 dev->bus_id, dev->driver->name);
 
 	if (dev->bus)
-		blocking_notifier_call_chain(&dev->bus->bus_notifier,
+		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 					     BUS_NOTIFY_BOUND_DRIVER, dev);
 
 	klist_add_tail(&dev->knode_driver, &dev->driver->klist_devices);
@@ -296,7 +296,7 @@
 		klist_remove(&dev->knode_driver);
 
 		if (dev->bus)
-			blocking_notifier_call_chain(&dev->bus->bus_notifier,
+			blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 						     BUS_NOTIFY_UNBIND_DRIVER,
 						     dev);