configfs: Add permission and ownership to configfs objects.

configfs always made item and attribute ownership root.root and
permissions based on a umask of 022.  Add ->setattr() to allow
chown(2)/chmod(2), and persist the changes for the lifetime of the
items and attributes.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
diff --git a/include/linux/configfs.h b/include/linux/configfs.h
index acffb8c..a7f0150 100644
--- a/include/linux/configfs.h
+++ b/include/linux/configfs.h
@@ -126,7 +126,7 @@
 
 
 struct configfs_attribute {
-	char			*ca_name;
+	const char		*ca_name;
 	struct module 		*ca_owner;
 	mode_t			ca_mode;
 };