dlm: do synchronized socket connect call

To avoid -EINPROGRESS cases on connect that just ends in a retry we just
call connect in a synchronized way to wait until its done. Since commit
dbb751ff ("fs: dlm: parallelize lowcomms socket handling") we have a
non ordered workqueue running for serving the DLM sockets that allows us
to call send/recv for each DLM socket connection in parallel. Before
each worker needed to wait until the previous worker was done and
probably the reason why connect() was called in an asynchronous way to
not block other workers. This is however not necessary anymore as other
socket handling workers don't need to wait.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>