crypto: engine - support for parallel requests based on retry mechanism

crypto: engine - support for parallel requests based on retry mechanism

Added support for executing multiple requests, in parallel,
for crypto engine based on a retry mechanism.
If hardware was unable to execute a backlog request, enqueue it
back in front of crypto-engine queue, to keep the order
of requests.

A new variable is added, retry_support (this is to keep the
backward compatibility of crypto-engine) , which keeps track
whether the hardware has support for retry mechanism and,
also, if can run multiple requests.

If do_one_request() returns:
>= 0: hardware executed the request successfully;
< 0: this is the old error path. If hardware has support for retry
mechanism, the request is put back in front of crypto-engine queue.
For backwards compatibility, if the retry support is not available,
the crypto-engine will work as before.
If hardware queue is full (-ENOSPC), requeue request regardless
of MAY_BACKLOG flag.
If hardware throws any other error code (like -EIO, -EINVAL,
-ENOMEM, etc.) only MAY_BACKLOG requests are enqueued back into
crypto-engine's queue, since the others can be dropped.

The new crypto_engine_alloc_init_and_set function, initializes
crypto-engine, sets the maximum size for crypto-engine software
queue (not hardcoded anymore) and the retry_support variable
is set, by default, to false.
On crypto_pump_requests(), if do_one_request() returns >= 0,
a new request is send to hardware, until there is no space in
hardware and do_one_request() returns < 0.

By default, retry_support is false and crypto-engine will
work as before - will send requests to hardware,
one-by-one, on crypto_pump_requests(), and complete it, on
crypto_finalize_request(), and so on.

To support multiple requests, in each driver, retry_support
must be set on true, and if do_one_request() returns an error
the request must not be freed, since it will be enqueued back
into crypto-engine's queue.

When all drivers, that use crypto-engine now, will be updated for
retry mechanism, the retry_support variable can be removed.

Signed-off-by: Iuliana Prodan <iuliana.prodan@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>