driver model: constify attribute groups

Let attribute group vectors be declared "const".  We'd
like to let most attribute metadata live in read-only
sections... this is a start.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/include/linux/attribute_container.h b/include/linux/attribute_container.h
index 794ad74..c3ab814 100644
--- a/include/linux/attribute_container.h
+++ b/include/linux/attribute_container.h
@@ -17,7 +17,7 @@
 	struct list_head	node;
 	struct klist		containers;
 	struct class		*class;
-	struct attribute_group	*grp;
+	const struct attribute_group *grp;
 	struct device_attribute **attrs;
 	int (*match)(struct attribute_container *, struct device *);
 #define	ATTRIBUTE_CONTAINER_NO_CLASSDEVS	0x01