In near future we will need to walk through the list of internal
drivers in reversed order. The simplest solution is to turn
singly linked list into a doubly linked list.
We will not need to start from the end really, so there's no tail
pointer kept.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NCole Robinson <crobinso@redhat.com>