fs: dlm: set is othercon flag

There is a is othercon flag which is never used, this patch will set it
and printout a warning if the othercon ever sends a dlm message which
should never be the case.

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