[DLM] Lowcomms nodeid range & initialisation fixes

Fix a few range & initialization bugs in lowcomms.
- max_nodeid is really the highest nodeid encountered, so all loops must include
it in their iterations.
- clean dlm_local_count & connection_idr so we can do a clean restart.
- Remove a spurious BUG_ON

Signed-Off-By: Patrick Caulfield <pcaulfie@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>