iw_cxgb4: clean up send_connect()

Clean up send_connect() and make use of t6 specific
active open request struct.

Acked-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Bharat Teja <bharat@chelsio.com>
Signed-off-by: Ganesh Goudar <ganeshgr@chelsio.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>