fs: dlm: fix sock release if listen fails

This patch fixes a double sock_release() call when the listen() is
called for the dlm lowcomms listen socket. The caller of
dlm_listen_for_all should never care about releasing the socket if
dlm_listen_for_all() fails, it's done now only once if listen() fails.

Cc: stable@vger.kernel.org
Fixes: 2dc6b115 ("fs: dlm: introduce generic listen")
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>