For memory savings it is sometimes desirable to use a single-linked list
instead of a double-linked list. However, the Linux kernel does not
provide a default implementation of a single-linked list.
Add a very simple single-linked list implementation to WLAN for general
use.
Change-Id: I2959f34649a0d8e0b312d9d67c81de17753b9b6c
CRs-Fixed: 2418493
