Previous version had not error handling.
Request could remain uncompleted.

Also in the case of DMA error, FLAGS_INIT is unset
and accelerator will be initialized again.

Buffer size allignment is checked.
Signed-off-by: NDmitry Kasatkin <dmitry.kasatkin@nokia.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>