ocfs2/net: fix uninitialized ret in o2net_send_message_vec()

mmotm/fs/ocfs2/cluster/tcp.c: In function ‘o2net_send_message_vec’:
mmotm/fs/ocfs2/cluster/tcp.c:980:6: warning: ‘ret’ may be used uninitialized in this function

It seems a real bug introduced by commit 9af0b38f (ocfs2/net:
Use wait_event() in o2net_send_message_vec()).

cc: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>