crypto: s5p-sss - Look for the next request in the queue

Currently, the driver enqueues a request only if the busy bit is
false. And every request initiates a dequeue. If 2 requests arrive
simultaneously, only one of them will be dequeued.

To avoid this senario, we will enqueue the next request irrespective
of the system condition (that is what queue is here for). Also
schedule at a tasklet immediatly after the current request is done.
The tasklet will dequeue the next request in the queue, giving
continuous loop. tasklet will exit if there are no requests in the
queue.

Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
CC: David S. Miller <davem@davemloft.net>
CC: <linux-samsung-soc@vger.kernel.org>
Acked-by: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>