SDP: BUG1343 - Polygraph test crashes machine

SDP: BUG1343 - Polygraph test crashes machine

No socket reference was taken before starting DREQ timeout.
cancel delayed work only remove the work if it is in the timer stage
before entered to the workqueue.
Because of that, sdp_dreq_timeout_work could be in the work queue
after the socket was destructed. and when the socket was reused
and the inlined work structre was resetted things went wrong.

Signed-off-by: Amir Vadai <amirv@mellanox.co.il>