When the side is in responder state and no active connection, the
kernel will send a request to start the connection. in the circumstance
of the peer keeps restarting, this case will cause the connection
keeping increasing and memory consuming.
Before start new connection, looking for if there is any connection
existing for the new pair, if it exists, don't creat new connection.

Change-Id: I8c38434824380ed46cd99dcd399d0300c7e80423
Signed-off-by: Ken Zhu <guigenz@codeaurora.org>