IB/cm: avoid reusing local ID

Use an increasing local ID to avoid re-using identifiers while
messages may still be outstanding on the old ID.  Without this, a
quick connect-disconnect-connect sequence can fail by matching
messages for the new connection with the old connection.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>