driver core: get rid of struct device's bus_id string array

Now that all users of bus_id is gone, we can remove it from struct
device.

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

diff --git a/lib/kobject.c b/lib/kobject.c
index 0487d1f..a6dec32 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -212,7 +212,7 @@
  * @fmt: format string used to build the name
  * @vargs: vargs to format the string.
  */
-static int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
+int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
 				  va_list vargs)
 {
 	const char *old_name = kobj->name;