Version 2.15 of ypserv has gone from the server, ypserv_2.17

seems to work fine in its place.

diff --git a/packages/nis/ypserv_2.15.bb b/packages/nis/ypserv_2.17.bb
similarity index 100%
rename from packages/nis/ypserv_2.15.bb
rename to packages/nis/ypserv_2.17.bb