tipc: kill unnecessary goto's

Remove a number of needless 'goto exit' in send_stream
when the socket is in an unconnected state.
This patch is cosmetic and does not alter the operation of
TIPC in any way.

Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Signed-off-by: Wang Weidong <wangweidong1@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>