vtysh: master is a non-sorted list

vtysh: master is a non-sorted list

The commit:
a798241265a5808083a06b14ce1637d1ddf6a45a

attempted to use sorted master lists to do faster lookups
by using a RB Tree.  Unfortunately the original code
was creating a list->cmp function *but* never using it.
If you look at the commit, it clearly shows that the
function listnode_add is used to insert but when you
look at that function it is a tail push.

Fixes: #6573
Namely now this ordering is preserved:
bgp as-path access-list originate-only permit ^$
bgp as-path access-list originate-only deny .*

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>