DLM: close othercon at send/receive error

If an error occurs in the sending / receiving process, if othercon
exists, sending / receiving processing using othercon may also result
in an error. We fix to pre-close othercon as well.

Signed-off-by: Tadashi Miyauchi <miyauchi@toshiba-tops.co.jp>
Signed-off-by: Tsutomu Owa <tsutomu.owa@toshiba.co.jp>
Signed-off-by: David Teigland <teigland@redhat.com>