kset: convert struct bus_device->drivers to use kset_create

Dynamically create the kset instead of declaring it statically.

Having 3 static kobjects in one structure is not only foolish, but ripe
for nasty race conditions if handled improperly.  We also rename the
field to catch any potential users of it (not that there should be
outside of the driver core...)

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

diff --git a/include/linux/device.h b/include/linux/device.h
index 82c2777..110ace0 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -54,7 +54,7 @@
 	struct module		* owner;
 
 	struct kset		subsys;
-	struct kset		drivers;
+	struct kset		*drivers_kset;
 	struct kset		*devices_kset;
 	struct klist		klist_devices;
 	struct klist		klist_drivers;