kobject: add sample code for how to use ksets/ktypes/kobjects

This is a more complex example showing how to create a kset and a ktype
and some default attributes for a group of kobjects.

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

diff --git a/samples/kobject/Makefile b/samples/kobject/Makefile
index cce16e9..4a19420 100644
--- a/samples/kobject/Makefile
+++ b/samples/kobject/Makefile
@@ -1 +1 @@
-obj-$(CONFIG_SAMPLE_KOBJECT) += kobject-example.o
+obj-$(CONFIG_SAMPLE_KOBJECT) += kobject-example.o kset-example.o