RDMA/qedr: Fix synchronization methods and memory leaks in qedr

Re-design of the iWARP CM related objects reference counting and
synchronization methods, to ensure operations are synchronized correctly
and that memory allocated for "ep" is properly released. Also makes sure
QP memory is not released before ep is finished accessing it.

Where as the QP object is created/destroyed by external operations, the ep
is created/destroyed by internal operations and represents the tcp
connection associated with the QP.

QP destruction flow:
- needs to wait for ep establishment to complete (either successfully or
  with error)
- needs to wait for ep disconnect to be fully posted to avoid a race
  condition of disconnect being called after reset.
- both the operations above don't always happen, so we use atomic flags to
  indicate whether the qp destruction flow needs to wait for these
  completions or not, if the destroy is called before these operations
  began, the flows will check the flags and not execute them ( connect /
  disconnect).

We use completion structure for waiting for the completions mentioned
above.

The QP refcnt was modified to kref object.  The EP has a kref added to it
to handle additional worker thread accessing it.

Memory Leaks - https://www.spinics.net/lists/linux-rdma/msg83762.html

Concurrency not managed correctly -
https://www.spinics.net/lists/linux-rdma/msg67949.html

Fixes: de0089e6 ("RDMA/qedr: Add iWARP connection management qp related callbacks")
Link: https://lore.kernel.org/r/20191027200451.28187-4-michal.kalderon@marvell.com


Reported-by: Chuck Lever <chuck.lever@oracle.com>
Reported-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Ariel Elior <ariel.elior@marvell.com>
Signed-off-by: Michal Kalderon <michal.kalderon@marvell.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>