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/drivers/base/bus.c b/drivers/base/bus.c
index 871607b..8335a10 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -935,6 +935,12 @@
 }
 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
 
+struct kset *bus_get_kset(struct bus_type *bus)
+{
+	return &bus->subsys;
+}
+EXPORT_SYMBOL_GPL(bus_get_kset);
+
 int __init buses_init(void)
 {
 	bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);