totemconfig: Knet nodeid must be < 65536

Knet limits maximum node id to 16-bit type. This was not ensured in
corosync and it was possible to set nodeid to value >= 65536 and
(surprisingly) most of the things were working quite well because of
overflow. corosync-cmapctl -m stats contained knet nodeid in
stats.knet. subtree, so for nodeid 65536 result was:

Can't get value of stats.knet.node0.link0.connected. Error
CS_ERR_NOT_EXIST

Commit implements checking of nodeid and limits it to KNET_MAX_HOST
value when knet is used.

Signed-off-by: Jan Friesse <jfriesse@redhat.com>
Reviewed-by: Christine Caulfield <ccaulfie@redhat.com>