driver core: add way to get to bus kset

This allows an easier way to get to the kset associated with a struct
bus_type (you have three to choose from...)  This will make it easier to
move these fields to be dynamic in a future patch.

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 313e0b3..3cc13c3 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -117,6 +117,8 @@
 #define BUS_NOTIFY_UNBIND_DRIVER	0x00000004 /* driver about to be
 						      unbound */
 
+extern struct kset *bus_get_kset(struct bus_type *bus);
+
 struct device_driver {
 	const char		* name;
 	struct bus_type		* bus;