crypto: marvell/cesa - fix memory leak

To: Boris Brezillon <boris.brezillon@free-electrons.com>,Arnaud Ebalard <arno@natisbad.org>,Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,Jason Cooper <jason@lakedaemon.net>

The local chain variable is not cleaned up if an error occurs in the middle
of DMA chain creation. Fix that by dropping the local chain variable and
using the dreq->chain field which will be cleaned up by
mv_cesa_dma_cleanup() in case of errors.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Reported-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>